| Message ID | 20151202080706.GA92803@kam.mff.cuni.cz |
|---|---|
| State | New |
| Headers | show |
On Wed, 2 Dec 2015, Jan Hubicka wrote: > Hi, > this patch removes flag_strict_aliasing kludge in expanding debug locations and > instead it introduces explicit parameter DEBUG that makes > set_mem_attributes_minus_bitpos to not affect alias sets. This is sanity > checked by comparing number of alias sets before and after at a time we > originally overwritten flag_strict_aliasing. > > I also added code to prevent memory attributes creation for !optimize and to > avoid get_alias_set computation for !flag_strict_aliasing. This slightly > optimizes -O0 builds but the results seems to be down in the noise (I would not > object to leave it out). > > The patch should fix at least one (latent?) bug that call_stmt expansion > invoke expand_debug_expr without clearing flag_strict_aliasing. > > Bootstrapped/regtested x86_64-linux, also tested with compare-debug, OK? First of all, why do debug MEMs need mem-attrs? Second, I'd rather refactor make_decl_rtl into a _raw part that can be used from both make_decl_rtl and make_decl_rtl_for_debug avoiding the debug parameter. I don't think any of this is suitable for stage3. Thanks, Richard. > Honza > > * cfgexpand.c: Include alias.h > (expand_debug_expr): Pass debug=true to set_mem_attributes. > (expand_debug_locations): Do not fiddle with flag_strict_aliasing; > sanity check that no new alias set was introduced. > * varasm.c: Include alias.h > (make_decl_rtl): New parameter DEBUG; pass it to set_mem_attributes. > (make_decl_rtl_for_debug): Do ont fiddle with flag_strict_aliasing; > assert that no new alias set was introduced. > * varasm.h (make_decl_rtl): New parameter debug. > * alias.h (num_alias_sets): New function. > * emit-rtl.c (set_mem_attributes_minus_bitpos): New parameter DEBUG; > exit early when not optimizing; do not introduce new alias set when > producing debug only attributes. > (set_mem_attributes): New parameter DEBUG. > * emit-rtl.h (set_mem_attributes, set_mem_attributes_minus_bitpos): > New parameters DEBUG. > (num_alias_sets): New function. > > Index: cfgexpand.c > =================================================================== > --- cfgexpand.c (revision 231122) > +++ cfgexpand.c (working copy) > @@ -73,6 +73,7 @@ along with GCC; see the file COPYING3. > #include "builtins.h" > #include "tree-chkp.h" > #include "rtl-chkp.h" > +#include "alias.h" > > /* Some systems use __main in a way incompatible with its use in gcc, in these > cases use the macros NAME__MAIN to give a quoted symbol and SYMBOL__MAIN to > @@ -4178,7 +4179,7 @@ expand_debug_expr (tree exp) > return NULL_RTX; > op0 = gen_rtx_CONST_STRING (Pmode, TREE_STRING_POINTER (exp)); > op0 = gen_rtx_MEM (BLKmode, op0); > - set_mem_attributes (op0, exp, 0); > + set_mem_attributes (op0, exp, 0, true); > return op0; > } > /* Fall through... */ > @@ -4346,7 +4347,7 @@ expand_debug_expr (tree exp) > return NULL; > > op0 = gen_rtx_MEM (mode, op0); > - set_mem_attributes (op0, exp, 0); > + set_mem_attributes (op0, exp, 0, true); > if (TREE_CODE (exp) == MEM_REF > && !is_gimple_mem_ref_addr (TREE_OPERAND (exp, 0))) > set_mem_expr (op0, NULL_TREE); > @@ -4372,7 +4373,7 @@ expand_debug_expr (tree exp) > > op0 = gen_rtx_MEM (mode, op0); > > - set_mem_attributes (op0, exp, 0); > + set_mem_attributes (op0, exp, 0, true); > set_mem_addr_space (op0, as); > > return op0; > @@ -4458,7 +4459,7 @@ expand_debug_expr (tree exp) > op0 = copy_rtx (op0); > if (op0 == orig_op0) > op0 = shallow_copy_rtx (op0); > - set_mem_attributes (op0, exp, 0); > + set_mem_attributes (op0, exp, 0, true); > } > > if (bitpos == 0 && mode == GET_MODE (op0)) > @@ -5219,12 +5220,11 @@ expand_debug_locations (void) > { > rtx_insn *insn; > rtx_insn *last = get_last_insn (); > - int save_strict_alias = flag_strict_aliasing; > > /* New alias sets while setting up memory attributes cause > -fcompare-debug failures, even though it doesn't bring about any > codegen changes. */ > - flag_strict_aliasing = 0; > + int num = num_alias_sets (); > > for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) > if (DEBUG_INSN_P (insn)) > @@ -5284,7 +5284,7 @@ expand_debug_locations (void) > avoid_complex_debug_insns (insn2, &INSN_VAR_LOCATION_LOC (insn2), 0); > } > > - flag_strict_aliasing = save_strict_alias; > + gcc_checking_assert (num == num_alias_sets ()); > } > > /* Performs swapping operands of commutative operations to expand > Index: varasm.c > =================================================================== > --- varasm.c (revision 231122) > +++ varasm.c (working copy) > @@ -52,6 +52,7 @@ along with GCC; see the file COPYING3. > #include "common/common-target.h" > #include "asan.h" > #include "rtl-iter.h" > +#include "alias.h" > > #ifdef XCOFF_DEBUGGING_INFO > #include "xcoffout.h" /* Needed for external data declarations. */ > @@ -1280,7 +1281,7 @@ ultimate_transparent_alias_target (tree > This is never called for PARM_DECL nodes. */ > > void > -make_decl_rtl (tree decl) > +make_decl_rtl (tree decl, bool debug) > { > const char *name = 0; > int reg_number; > @@ -1470,7 +1471,7 @@ make_decl_rtl (tree decl) > > x = gen_rtx_MEM (DECL_MODE (decl), x); > if (TREE_CODE (decl) != FUNCTION_DECL) > - set_mem_attributes (x, decl, 1); > + set_mem_attributes (x, decl, 1, debug); > SET_DECL_RTL (decl, x); > > /* Optionally set flags or add text to the name to record information > @@ -1487,27 +1488,25 @@ make_decl_rtl (tree decl) > rtx > make_decl_rtl_for_debug (tree decl) > { > - unsigned int save_aliasing_flag; > rtx rtl; > > if (DECL_RTL_SET_P (decl)) > return DECL_RTL (decl); > > - /* Kludge alert! Somewhere down the call chain, make_decl_rtl will > - call new_alias_set. If running with -fcompare-debug, sometimes > - we do not want to create alias sets that will throw the alias > - numbers off in the comparison dumps. So... clearing > - flag_strict_aliasing will keep new_alias_set() from creating a > - new set. */ > - save_aliasing_flag = flag_strict_aliasing; > - flag_strict_aliasing = 0; > + int num = num_alias_sets (); > > + make_decl_rtl (decl, true); > rtl = DECL_RTL (decl); > /* Reset DECL_RTL back, as various parts of the compiler expects > DECL_RTL set meaning it is actually going to be output. */ > SET_DECL_RTL (decl, NULL); > + > + /* Be sure that make_decl_rtl will not cal lnew_alias set. > + If running with -fcompare-debug, sometimes > + we do not want to create alias sets that will throw the alias > + numbers off in the comparison dumps. */ > + gcc_checking_assert (num == num_alias_sets ()); > > - flag_strict_aliasing = save_aliasing_flag; > return rtl; > } > > Index: varasm.h > =================================================================== > --- varasm.h (revision 231122) > +++ varasm.h (working copy) > @@ -28,7 +28,7 @@ along with GCC; see the file COPYING3. > extern tree cold_function_name; > > extern tree tree_output_constant_def (tree); > -extern void make_decl_rtl (tree); > +extern void make_decl_rtl (tree, bool debug = false); > extern rtx make_decl_rtl_for_debug (tree); > extern void make_decl_one_only (tree, tree); > extern int supports_one_only (void); > Index: alias.h > =================================================================== > --- alias.h (revision 231122) > +++ alias.h (working copy) > @@ -25,6 +25,7 @@ extern alias_set_type get_alias_set (tre > extern alias_set_type get_deref_alias_set (tree); > extern alias_set_type get_varargs_alias_set (void); > extern alias_set_type get_frame_alias_set (void); > +extern int num_alias_sets (void); > extern tree component_uses_parent_alias_set_from (const_tree); > extern bool alias_set_subset_of (alias_set_type, alias_set_type); > extern void record_alias_subset (alias_set_type, alias_set_type); > Index: emit-rtl.c > =================================================================== > --- emit-rtl.c (revision 231122) > +++ emit-rtl.c (working copy) > @@ -1738,16 +1738,20 @@ get_mem_align_offset (rtx mem, unsigned > /* Given REF (a MEM) and T, either the type of X or the expression > corresponding to REF, set the memory attributes. OBJECTP is nonzero > if we are making a new object of this type. BITPOS is nonzero if > - there is an offset outstanding on T that will be applied later. */ > + there is an offset outstanding on T that will be applied later. > + if DEBUG is true, assume that the MEM will be used only for debug > + insns. */ > > void > set_mem_attributes_minus_bitpos (rtx ref, tree t, int objectp, > - HOST_WIDE_INT bitpos) > + HOST_WIDE_INT bitpos, bool debug) > { > HOST_WIDE_INT apply_bitpos = 0; > tree type; > struct mem_attrs attrs, *defattrs, *refattrs; > addr_space_t as; > + bool global_var = false; > + tree orig_t = t; > > /* It can happen that type_for_mode was given a mode for which there > is no language-level type. In which case it returns NULL, which > @@ -1759,18 +1763,8 @@ set_mem_attributes_minus_bitpos (rtx ref > if (type == error_mark_node) > return; > > - /* If we have already set DECL_RTL = ref, get_alias_set will get the > - wrong answer, as it assumes that DECL_RTL already has the right alias > - info. Callers should not set DECL_RTL until after the call to > - set_mem_attributes. */ > - gcc_assert (!DECL_P (t) || ref != DECL_RTL_IF_SET (t)); > - > memset (&attrs, 0, sizeof (attrs)); > > - /* Get the alias set from the expression or type (perhaps using a > - front-end routine) and use it. */ > - attrs.alias = get_alias_set (t); > - > MEM_VOLATILE_P (ref) |= TYPE_VOLATILE (type); > MEM_POINTER (ref) = POINTER_TYPE_P (type); > > @@ -1829,6 +1823,12 @@ set_mem_attributes_minus_bitpos (rtx ref > { > tree base; > > + if (TREE_CODE (t) == CONST_DECL > + || (TREE_CODE (t) == VAR_DECL > + && auto_var_in_fn_p (t, current_function_decl)) > + || (TREE_CODE (t) == LABEL_DECL && DECL_NONLOCAL (t))) > + global_var = true; > + > if (TREE_THIS_VOLATILE (t)) > MEM_VOLATILE_P (ref) = 1; > > @@ -1866,13 +1866,20 @@ set_mem_attributes_minus_bitpos (rtx ref > as = TYPE_ADDR_SPACE (TREE_TYPE (base)); > } > > + /* When not optimizing, there is no need to attach memory attributes > + unless we produce DECL_RTL of declaration that may later be used in a > + function that is optimized. */ > + if (!optimize && !global_var) > + return; > + > /* If this expression uses it's parent's alias set, mark it such > that we won't change it. */ > - if (component_uses_parent_alias_set_from (t) != NULL_TREE) > + if (!debug && (flag_strict_aliasing || global_var) > + && component_uses_parent_alias_set_from (t) != NULL_TREE) > MEM_KEEP_ALIAS_SET_P (ref) = 1; > > /* If this is a decl, set the attributes of the MEM from it. */ > - if (DECL_P (t)) > + else if (DECL_P (t)) > { > attrs.expr = t; > attrs.offset_known_p = true; > @@ -1962,6 +1969,11 @@ set_mem_attributes_minus_bitpos (rtx ref > obj_align = (obj_bitpos & -obj_bitpos); > attrs.align = MAX (attrs.align, obj_align); > } > + /* When not optimizing, there is no need to attach memory attributes > + unless we produce DECL_RTL of declaration that may later be used in a > + function that is optimized. */ > + else if (!global_var && !optimize) > + return; > > if (tree_fits_uhwi_p (new_size)) > { > @@ -1980,15 +1992,29 @@ set_mem_attributes_minus_bitpos (rtx ref > attrs.size += apply_bitpos / BITS_PER_UNIT; > } > > + /* Get the alias set from the expression or type (perhaps using a > + front-end routine) and use it. Never produce new alias sets when > + the memory reference is used only for debug (so the alias numbers > + are stable) and with !flag_strict_aliasing for all function local RTLs. */ > + if (!debug && (flag_strict_aliasing || global_var)) > + { > + /* If we have already set DECL_RTL = ref, get_alias_set will get the > + wrong answer, as it assumes that DECL_RTL already has the right alias > + info. Callers should not set DECL_RTL until after the call to > + set_mem_attributes. */ > + gcc_assert (!DECL_P (orig_t) || ref != DECL_RTL_IF_SET (orig_t)); > + attrs.alias = get_alias_set (orig_t); > + } > + > /* Now set the attributes we computed above. */ > attrs.addrspace = as; > set_mem_attrs (ref, &attrs); > } > > void > -set_mem_attributes (rtx ref, tree t, int objectp) > +set_mem_attributes (rtx ref, tree t, int objectp, bool debug) > { > - set_mem_attributes_minus_bitpos (ref, t, objectp, 0); > + set_mem_attributes_minus_bitpos (ref, t, objectp, 0, debug); > } > > /* Set the alias set of MEM to SET. */ > Index: emit-rtl.h > =================================================================== > --- emit-rtl.h (revision 231122) > +++ emit-rtl.h (working copy) > @@ -484,13 +484,16 @@ extern rtx offset_address (rtx, rtx, uns > > /* Given REF, a MEM, and T, either the type of X or the expression > corresponding to REF, set the memory attributes. OBJECTP is nonzero > - if we are making a new object of this type. */ > -extern void set_mem_attributes (rtx, tree, int); > + if we are making a new object of this type. > + If DEBUG is true, the memory expression will be used only for debug > + statements and in that case avoid creation of new alias set. */ > +extern void set_mem_attributes (rtx, tree, int, bool debug = false); > > /* Similar, except that BITPOS has not yet been applied to REF, so if > we alter MEM_OFFSET according to T then we should subtract BITPOS > expecting that it'll be added back in later. */ > -extern void set_mem_attributes_minus_bitpos (rtx, tree, int, HOST_WIDE_INT); > +extern void set_mem_attributes_minus_bitpos (rtx, tree, int, HOST_WIDE_INT, > + bool debug = false); > > /* Return OFFSET if XEXP (MEM, 0) - OFFSET is known to be ALIGN > bits aligned for 0 <= OFFSET < ALIGN / BITS_PER_UNIT, or > Index: alias.c > =================================================================== > --- alias.c (revision 231146) > +++ alias.c (working copy) > @@ -1096,6 +1096,17 @@ new_alias_set (void) > return 0; > } > > +/* Return number of alias sets; used for sanity checking that we did not > + introduced new ones for debug statements. */ > + > +int > +num_alias_sets (void) > +{ > + if (!alias_sets) > + return 0; > + return alias_sets->length (); > +} > + > /* Indicate that things in SUBSET can alias things in SUPERSET, but that > not everything that aliases SUPERSET also aliases SUBSET. For example, > in C, a store to an `int' can alias a load of a structure containing an > >
On Wed, Dec 02, 2015 at 10:05:13AM +0100, Richard Biener wrote: > On Wed, 2 Dec 2015, Jan Hubicka wrote: > > > Hi, > > this patch removes flag_strict_aliasing kludge in expanding debug locations and > > instead it introduces explicit parameter DEBUG that makes > > set_mem_attributes_minus_bitpos to not affect alias sets. This is sanity > > checked by comparing number of alias sets before and after at a time we > > originally overwritten flag_strict_aliasing. > > > > I also added code to prevent memory attributes creation for !optimize and to > > avoid get_alias_set computation for !flag_strict_aliasing. This slightly > > optimizes -O0 builds but the results seems to be down in the noise (I would not > > object to leave it out). > > > > The patch should fix at least one (latent?) bug that call_stmt expansion > > invoke expand_debug_expr without clearing flag_strict_aliasing. > > > > Bootstrapped/regtested x86_64-linux, also tested with compare-debug, OK? > > First of all, why do debug MEMs need mem-attrs? For aliasing purposes, like any other MEMs. var-tracking needs to be able to find out if some store through say some pointer could alias certain debug MEM (then we need to flush the corresponding VALUEs), or not (then that VALUE can be still considered live at that MEM location). Jakub
On Wed, 2 Dec 2015, Jakub Jelinek wrote: > On Wed, Dec 02, 2015 at 10:05:13AM +0100, Richard Biener wrote: > > On Wed, 2 Dec 2015, Jan Hubicka wrote: > > > > > Hi, > > > this patch removes flag_strict_aliasing kludge in expanding debug locations and > > > instead it introduces explicit parameter DEBUG that makes > > > set_mem_attributes_minus_bitpos to not affect alias sets. This is sanity > > > checked by comparing number of alias sets before and after at a time we > > > originally overwritten flag_strict_aliasing. > > > > > > I also added code to prevent memory attributes creation for !optimize and to > > > avoid get_alias_set computation for !flag_strict_aliasing. This slightly > > > optimizes -O0 builds but the results seems to be down in the noise (I would not > > > object to leave it out). > > > > > > The patch should fix at least one (latent?) bug that call_stmt expansion > > > invoke expand_debug_expr without clearing flag_strict_aliasing. > > > > > > Bootstrapped/regtested x86_64-linux, also tested with compare-debug, OK? > > > > First of all, why do debug MEMs need mem-attrs? > > For aliasing purposes, like any other MEMs. var-tracking needs to be able > to find out if some store through say some pointer could alias certain debug > MEM (then we need to flush the corresponding VALUEs), or not (then that > VALUE can be still considered live at that MEM location). Ok, so we then pessimize the alias-set for all of them (when they don't have a DECL_RTL already) to use alias-set zero even if we wouldn't need to create a new alias set? (and even if I don't see what issues that would cause apart from "messing up the dumps" which should be fixed by stripping alias sets from dumps) Richard.
> On Wed, 2 Dec 2015, Jakub Jelinek wrote: > > > On Wed, Dec 02, 2015 at 10:05:13AM +0100, Richard Biener wrote: > > > On Wed, 2 Dec 2015, Jan Hubicka wrote: > > > > > > > Hi, > > > > this patch removes flag_strict_aliasing kludge in expanding debug locations and > > > > instead it introduces explicit parameter DEBUG that makes > > > > set_mem_attributes_minus_bitpos to not affect alias sets. This is sanity > > > > checked by comparing number of alias sets before and after at a time we > > > > originally overwritten flag_strict_aliasing. > > > > > > > > I also added code to prevent memory attributes creation for !optimize and to > > > > avoid get_alias_set computation for !flag_strict_aliasing. This slightly > > > > optimizes -O0 builds but the results seems to be down in the noise (I would not > > > > object to leave it out). > > > > > > > > The patch should fix at least one (latent?) bug that call_stmt expansion > > > > invoke expand_debug_expr without clearing flag_strict_aliasing. > > > > > > > > Bootstrapped/regtested x86_64-linux, also tested with compare-debug, OK? > > > > > > First of all, why do debug MEMs need mem-attrs? > > > > For aliasing purposes, like any other MEMs. var-tracking needs to be able > > to find out if some store through say some pointer could alias certain debug > > MEM (then we need to flush the corresponding VALUEs), or not (then that > > VALUE can be still considered live at that MEM location). > > Ok, so we then pessimize the alias-set for all of them (when they > don't have a DECL_RTL already) to use alias-set zero even if we > wouldn't need to create a new alias set? (and even if I don't see > what issues that would cause apart from "messing up the dumps" which > should be fixed by stripping alias sets from dumps) Breaking out code into make_decl_rtl_raw is also easy, since set_mem_attributes is called at very end of make_decl_rtl. Jakub, in https://gcc.gnu.org/ml/gcc-patches/2015-12/msg00316.html I make get_alias_set to do the job even in !flas_strict_aliasing because this is needed to make it possible to mix flag_strict_aliasing and !flag_strict_aliasing functions in one translation unit. We do that during LTO. I wonder how to reproduce the messed up dumps here with that patch and if stripping the alias sets would be OK? Indeed getting extra alias sets should not cause codegen differences. Honza > > Richard.
Index: cfgexpand.c =================================================================== --- cfgexpand.c (revision 231122) +++ cfgexpand.c (working copy) @@ -73,6 +73,7 @@ along with GCC; see the file COPYING3. #include "builtins.h" #include "tree-chkp.h" #include "rtl-chkp.h" +#include "alias.h" /* Some systems use __main in a way incompatible with its use in gcc, in these cases use the macros NAME__MAIN to give a quoted symbol and SYMBOL__MAIN to @@ -4178,7 +4179,7 @@ expand_debug_expr (tree exp) return NULL_RTX; op0 = gen_rtx_CONST_STRING (Pmode, TREE_STRING_POINTER (exp)); op0 = gen_rtx_MEM (BLKmode, op0); - set_mem_attributes (op0, exp, 0); + set_mem_attributes (op0, exp, 0, true); return op0; } /* Fall through... */ @@ -4346,7 +4347,7 @@ expand_debug_expr (tree exp) return NULL; op0 = gen_rtx_MEM (mode, op0); - set_mem_attributes (op0, exp, 0); + set_mem_attributes (op0, exp, 0, true); if (TREE_CODE (exp) == MEM_REF && !is_gimple_mem_ref_addr (TREE_OPERAND (exp, 0))) set_mem_expr (op0, NULL_TREE); @@ -4372,7 +4373,7 @@ expand_debug_expr (tree exp) op0 = gen_rtx_MEM (mode, op0); - set_mem_attributes (op0, exp, 0); + set_mem_attributes (op0, exp, 0, true); set_mem_addr_space (op0, as); return op0; @@ -4458,7 +4459,7 @@ expand_debug_expr (tree exp) op0 = copy_rtx (op0); if (op0 == orig_op0) op0 = shallow_copy_rtx (op0); - set_mem_attributes (op0, exp, 0); + set_mem_attributes (op0, exp, 0, true); } if (bitpos == 0 && mode == GET_MODE (op0)) @@ -5219,12 +5220,11 @@ expand_debug_locations (void) { rtx_insn *insn; rtx_insn *last = get_last_insn (); - int save_strict_alias = flag_strict_aliasing; /* New alias sets while setting up memory attributes cause -fcompare-debug failures, even though it doesn't bring about any codegen changes. */ - flag_strict_aliasing = 0; + int num = num_alias_sets (); for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) if (DEBUG_INSN_P (insn)) @@ -5284,7 +5284,7 @@ expand_debug_locations (void) avoid_complex_debug_insns (insn2, &INSN_VAR_LOCATION_LOC (insn2), 0); } - flag_strict_aliasing = save_strict_alias; + gcc_checking_assert (num == num_alias_sets ()); } /* Performs swapping operands of commutative operations to expand Index: varasm.c =================================================================== --- varasm.c (revision 231122) +++ varasm.c (working copy) @@ -52,6 +52,7 @@ along with GCC; see the file COPYING3. #include "common/common-target.h" #include "asan.h" #include "rtl-iter.h" +#include "alias.h" #ifdef XCOFF_DEBUGGING_INFO #include "xcoffout.h" /* Needed for external data declarations. */ @@ -1280,7 +1281,7 @@ ultimate_transparent_alias_target (tree This is never called for PARM_DECL nodes. */ void -make_decl_rtl (tree decl) +make_decl_rtl (tree decl, bool debug) { const char *name = 0; int reg_number; @@ -1470,7 +1471,7 @@ make_decl_rtl (tree decl) x = gen_rtx_MEM (DECL_MODE (decl), x); if (TREE_CODE (decl) != FUNCTION_DECL) - set_mem_attributes (x, decl, 1); + set_mem_attributes (x, decl, 1, debug); SET_DECL_RTL (decl, x); /* Optionally set flags or add text to the name to record information @@ -1487,27 +1488,25 @@ make_decl_rtl (tree decl) rtx make_decl_rtl_for_debug (tree decl) { - unsigned int save_aliasing_flag; rtx rtl; if (DECL_RTL_SET_P (decl)) return DECL_RTL (decl); - /* Kludge alert! Somewhere down the call chain, make_decl_rtl will - call new_alias_set. If running with -fcompare-debug, sometimes - we do not want to create alias sets that will throw the alias - numbers off in the comparison dumps. So... clearing - flag_strict_aliasing will keep new_alias_set() from creating a - new set. */ - save_aliasing_flag = flag_strict_aliasing; - flag_strict_aliasing = 0; + int num = num_alias_sets (); + make_decl_rtl (decl, true); rtl = DECL_RTL (decl); /* Reset DECL_RTL back, as various parts of the compiler expects DECL_RTL set meaning it is actually going to be output. */ SET_DECL_RTL (decl, NULL); + + /* Be sure that make_decl_rtl will not cal lnew_alias set. + If running with -fcompare-debug, sometimes + we do not want to create alias sets that will throw the alias + numbers off in the comparison dumps. */ + gcc_checking_assert (num == num_alias_sets ()); - flag_strict_aliasing = save_aliasing_flag; return rtl; } Index: varasm.h =================================================================== --- varasm.h (revision 231122) +++ varasm.h (working copy) @@ -28,7 +28,7 @@ along with GCC; see the file COPYING3. extern tree cold_function_name; extern tree tree_output_constant_def (tree); -extern void make_decl_rtl (tree); +extern void make_decl_rtl (tree, bool debug = false); extern rtx make_decl_rtl_for_debug (tree); extern void make_decl_one_only (tree, tree); extern int supports_one_only (void); Index: alias.h =================================================================== --- alias.h (revision 231122) +++ alias.h (working copy) @@ -25,6 +25,7 @@ extern alias_set_type get_alias_set (tre extern alias_set_type get_deref_alias_set (tree); extern alias_set_type get_varargs_alias_set (void); extern alias_set_type get_frame_alias_set (void); +extern int num_alias_sets (void); extern tree component_uses_parent_alias_set_from (const_tree); extern bool alias_set_subset_of (alias_set_type, alias_set_type); extern void record_alias_subset (alias_set_type, alias_set_type); Index: emit-rtl.c =================================================================== --- emit-rtl.c (revision 231122) +++ emit-rtl.c (working copy) @@ -1738,16 +1738,20 @@ get_mem_align_offset (rtx mem, unsigned /* Given REF (a MEM) and T, either the type of X or the expression corresponding to REF, set the memory attributes. OBJECTP is nonzero if we are making a new object of this type. BITPOS is nonzero if - there is an offset outstanding on T that will be applied later. */ + there is an offset outstanding on T that will be applied later. + if DEBUG is true, assume that the MEM will be used only for debug + insns. */ void set_mem_attributes_minus_bitpos (rtx ref, tree t, int objectp, - HOST_WIDE_INT bitpos) + HOST_WIDE_INT bitpos, bool debug) { HOST_WIDE_INT apply_bitpos = 0; tree type; struct mem_attrs attrs, *defattrs, *refattrs; addr_space_t as; + bool global_var = false; + tree orig_t = t; /* It can happen that type_for_mode was given a mode for which there is no language-level type. In which case it returns NULL, which @@ -1759,18 +1763,8 @@ set_mem_attributes_minus_bitpos (rtx ref if (type == error_mark_node) return; - /* If we have already set DECL_RTL = ref, get_alias_set will get the - wrong answer, as it assumes that DECL_RTL already has the right alias - info. Callers should not set DECL_RTL until after the call to - set_mem_attributes. */ - gcc_assert (!DECL_P (t) || ref != DECL_RTL_IF_SET (t)); - memset (&attrs, 0, sizeof (attrs)); - /* Get the alias set from the expression or type (perhaps using a - front-end routine) and use it. */ - attrs.alias = get_alias_set (t); - MEM_VOLATILE_P (ref) |= TYPE_VOLATILE (type); MEM_POINTER (ref) = POINTER_TYPE_P (type); @@ -1829,6 +1823,12 @@ set_mem_attributes_minus_bitpos (rtx ref { tree base; + if (TREE_CODE (t) == CONST_DECL + || (TREE_CODE (t) == VAR_DECL + && auto_var_in_fn_p (t, current_function_decl)) + || (TREE_CODE (t) == LABEL_DECL && DECL_NONLOCAL (t))) + global_var = true; + if (TREE_THIS_VOLATILE (t)) MEM_VOLATILE_P (ref) = 1; @@ -1866,13 +1866,20 @@ set_mem_attributes_minus_bitpos (rtx ref as = TYPE_ADDR_SPACE (TREE_TYPE (base)); } + /* When not optimizing, there is no need to attach memory attributes + unless we produce DECL_RTL of declaration that may later be used in a + function that is optimized. */ + if (!optimize && !global_var) + return; + /* If this expression uses it's parent's alias set, mark it such that we won't change it. */ - if (component_uses_parent_alias_set_from (t) != NULL_TREE) + if (!debug && (flag_strict_aliasing || global_var) + && component_uses_parent_alias_set_from (t) != NULL_TREE) MEM_KEEP_ALIAS_SET_P (ref) = 1; /* If this is a decl, set the attributes of the MEM from it. */ - if (DECL_P (t)) + else if (DECL_P (t)) { attrs.expr = t; attrs.offset_known_p = true; @@ -1962,6 +1969,11 @@ set_mem_attributes_minus_bitpos (rtx ref obj_align = (obj_bitpos & -obj_bitpos); attrs.align = MAX (attrs.align, obj_align); } + /* When not optimizing, there is no need to attach memory attributes + unless we produce DECL_RTL of declaration that may later be used in a + function that is optimized. */ + else if (!global_var && !optimize) + return; if (tree_fits_uhwi_p (new_size)) { @@ -1980,15 +1992,29 @@ set_mem_attributes_minus_bitpos (rtx ref attrs.size += apply_bitpos / BITS_PER_UNIT; } + /* Get the alias set from the expression or type (perhaps using a + front-end routine) and use it. Never produce new alias sets when + the memory reference is used only for debug (so the alias numbers + are stable) and with !flag_strict_aliasing for all function local RTLs. */ + if (!debug && (flag_strict_aliasing || global_var)) + { + /* If we have already set DECL_RTL = ref, get_alias_set will get the + wrong answer, as it assumes that DECL_RTL already has the right alias + info. Callers should not set DECL_RTL until after the call to + set_mem_attributes. */ + gcc_assert (!DECL_P (orig_t) || ref != DECL_RTL_IF_SET (orig_t)); + attrs.alias = get_alias_set (orig_t); + } + /* Now set the attributes we computed above. */ attrs.addrspace = as; set_mem_attrs (ref, &attrs); } void -set_mem_attributes (rtx ref, tree t, int objectp) +set_mem_attributes (rtx ref, tree t, int objectp, bool debug) { - set_mem_attributes_minus_bitpos (ref, t, objectp, 0); + set_mem_attributes_minus_bitpos (ref, t, objectp, 0, debug); } /* Set the alias set of MEM to SET. */ Index: emit-rtl.h =================================================================== --- emit-rtl.h (revision 231122) +++ emit-rtl.h (working copy) @@ -484,13 +484,16 @@ extern rtx offset_address (rtx, rtx, uns /* Given REF, a MEM, and T, either the type of X or the expression corresponding to REF, set the memory attributes. OBJECTP is nonzero - if we are making a new object of this type. */ -extern void set_mem_attributes (rtx, tree, int); + if we are making a new object of this type. + If DEBUG is true, the memory expression will be used only for debug + statements and in that case avoid creation of new alias set. */ +extern void set_mem_attributes (rtx, tree, int, bool debug = false); /* Similar, except that BITPOS has not yet been applied to REF, so if we alter MEM_OFFSET according to T then we should subtract BITPOS expecting that it'll be added back in later. */ -extern void set_mem_attributes_minus_bitpos (rtx, tree, int, HOST_WIDE_INT); +extern void set_mem_attributes_minus_bitpos (rtx, tree, int, HOST_WIDE_INT, + bool debug = false); /* Return OFFSET if XEXP (MEM, 0) - OFFSET is known to be ALIGN bits aligned for 0 <= OFFSET < ALIGN / BITS_PER_UNIT, or Index: alias.c =================================================================== --- alias.c (revision 231146) +++ alias.c (working copy) @@ -1096,6 +1096,17 @@ new_alias_set (void) return 0; } +/* Return number of alias sets; used for sanity checking that we did not + introduced new ones for debug statements. */ + +int +num_alias_sets (void) +{ + if (!alias_sets) + return 0; + return alias_sets->length (); +} + /* Indicate that things in SUBSET can alias things in SUPERSET, but that not everything that aliases SUPERSET also aliases SUBSET. For example, in C, a store to an `int' can alias a load of a structure containing an