| Message ID | 8b3a94a09d35d51da2b0330ecff543d6dbcbe029.camel@med.uni-goettingen.de |
|---|---|
| State | New |
| Headers | show |
| Series | [v4] Fix ICE when mixing VLAs and statement expressions [PR91038] | expand |
On 10/17/21 09:52, Uecker, Martin wrote: > > > Here is the 4th version of the patch. I tried to implement > Jason's suggestion and this also fixes the problem. But > I am not sure I understand the condition on > the TREE_SIDE_EFFECTS ... Checking TREE_SIDE_EFFECTS filters out many trivial cases that we don't need to worry about. I think we also want to check variably_modified_type_p, which ought to avoid the OMP problem below. > And there is now another problem: > > c_finish_omp_for in c-family/c-omp.c does not seem > to understand the expressions anymore and I get a test > failure in > > testsuite/c-c++-common/gomp/for-5.c > > where I now get an "invalid increment expression" > instead of the expected error. > (bootstrapping and all other tests work fine) > > > Martin > > > > > Fix ICE when mixing VLAs and statement expressions [PR91038] > > When returning VM-types from statement expressions, this can > lead to an ICE when declarations from the statement expression > are referred to later. Most of these issues can be addressed by > gimplifying the base expression earlier in gimplify_compound_lval. > > Another issue is fixed by adding SAVE_EXPRs in pointer_int_sum > in the FE to force a correct order of evaluation. This fixes > PR91038 and some of the test cases from PR29970 (structs with > VLA members need further work). > > > 2021-08-01 Martin Uecker <muecker@gwdg.de> > > 2021-08-01 Martin Uecker <muecker@gwdg.de> > > gcc/ > PR c/91038 > PR c/29970 > > * gimplify.c (gimplify_var_or_parm_decl): Update comment. > (gimplify_compound_lval): > Gimplify base expression first. > (gimplify_target_expr): Add comment. > * c-family/c- > common.c (pointer_int_sum): Wrap pointer > operand in SAVE_EXPR and also it to the integer > argument. > > gcc/testsuite/ > PR c/91038 > PR c/29970 > * gcc.dg/vla-stexp-3.c: > New test. > * gcc.dg/vla-stexp-4.c: New test. > * gcc.dg/vla-stexp-5.c: New test. > * > gcc.dg/vla-stexp-6.c: New test. > * gcc.dg/vla-stexp-7.c: New test. > * gcc.dg/vla-stexp- > 8.c: New test. > * gcc.dg/vla-stexp-9.c: New test. > > > diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c > index 9d19e352725..522085664f5 100644 > --- a/gcc/c-family/c-common.c > +++ b/gcc/c-family/c-common.c > @@ -3348,6 +3348,16 @@ pointer_int_sum (location_t loc, enum tree_code resultcode, > intop = convert (c_common_type_for_size (TYPE_PRECISION (sizetype), > TYPE_UNSIGNED (sizetype)), intop); > > + /* Wrap the pointer expression in a SAVE_EXPR to make sure it > + * is evaluated first because the size expression may depend on it > + * for VM types. > + */ We usually don't give the trailing */ its own line. > + if (TREE_SIDE_EFFECTS (size_exp)) > + { > + ptrop = build1_loc (loc, SAVE_EXPR, TREE_TYPE (ptrop), ptrop); Why not use the save_expr function? > + intop = build2 (COMPOUND_EXPR, TREE_TYPE (intop), ptrop, intop); > + } > + > /* Replace the integer argument with a suitable product by the object size. > Do this multiplication as signed, then convert to the appropriate type > for the pointer operation and disregard an overflow that occurred only > diff --git a/gcc/gimplify.c b/gcc/gimplify.c > index d8e4b139349..be5b00b6716 100644 > --- a/gcc/gimplify.c > +++ b/gcc/gimplify.c > @@ -2958,7 +2958,10 @@ gimplify_var_or_parm_decl (tree *expr_p) > declaration, for which we've already issued an error. It would > be really nice if the front end wouldn't leak these at all. > Currently the only known culprit is C++ destructors, as seen > - in g++.old-deja/g++.jason/binding.C. */ > + in g++.old-deja/g++.jason/binding.C. > + Another possible culpit are size expressions for variably modified > + types which are lost in the FE or not gimplified correctly. > + */ As above. > if (VAR_P (decl) > && !DECL_SEEN_IN_BIND_EXPR_P (decl) > && !TREE_STATIC (decl) && !DECL_EXTERNAL (decl) > @@ -3103,16 +3106,22 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p, > expression until we deal with any variable bounds, sizes, or > positions in order to deal with PLACEHOLDER_EXPRs. > > - So we do this in three steps. First we deal with the annotations > - for any variables in the components, then we gimplify the base, > - then we gimplify any indices, from left to right. */ > + The base expression may contain a statement expression that > + has declarations used in size expressions, so has to be > + gimplified before gimplifying the size expressions. > + > + So we do this in three steps. First we deal with variable > + bounds, sizes, and positions, then we gimplify the base, > + then we deal with the annotations for any variables in the > + components and any indices, from left to right. */ > + > for (i = expr_stack.length () - 1; i >= 0; i--) > { > tree t = expr_stack[i]; > > if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) > { > - /* Gimplify the low bound and element type size and put them into > + /* Deal with the low bound and element type size and put them into > the ARRAY_REF. If these values are set, they have already been > gimplified. */ > if (TREE_OPERAND (t, 2) == NULL_TREE) > @@ -3121,18 +3130,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p, > if (!is_gimple_min_invariant (low)) > { > TREE_OPERAND (t, 2) = low; > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, > - post_p, is_gimple_reg, > - fb_rvalue); > - ret = MIN (ret, tret); > } > } > - else > - { > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > - is_gimple_reg, fb_rvalue); > - ret = MIN (ret, tret); > - } > > if (TREE_OPERAND (t, 3) == NULL_TREE) > { > @@ -3149,18 +3148,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p, > elmt_size, factor); > > TREE_OPERAND (t, 3) = elmt_size; > - tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, > - post_p, is_gimple_reg, > - fb_rvalue); > - ret = MIN (ret, tret); > } > } > - else > - { > - tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p, > - is_gimple_reg, fb_rvalue); > - ret = MIN (ret, tret); > - } > } > else if (TREE_CODE (t) == COMPONENT_REF) > { > @@ -3180,18 +3169,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p, > offset, factor); > > TREE_OPERAND (t, 2) = offset; > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, > - post_p, is_gimple_reg, > - fb_rvalue); > - ret = MIN (ret, tret); > } > } > - else > - { > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > - is_gimple_reg, fb_rvalue); > - ret = MIN (ret, tret); > - } > } > } > > @@ -3202,21 +3181,34 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p, > fallback | fb_lvalue); > ret = MIN (ret, tret); > > - /* And finally, the indices and operands of ARRAY_REF. During this > - loop we also remove any useless conversions. */ > + /* Step 3: gimplify size expressions and the indices and operands of > + ARRAY_REF. During this loop we also remove any useless conversions. */ > + > for (; expr_stack.length () > 0; ) > { > tree t = expr_stack.pop (); > > if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) > { > + /* Gimplify the low bound and element type size. */ > + tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > + is_gimple_reg, fb_rvalue); > + ret = MIN (ret, tret); > + > + tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p, > + is_gimple_reg, fb_rvalue); > + ret = MIN (ret, tret); > + > /* Gimplify the dimension. */ > - if (!is_gimple_min_invariant (TREE_OPERAND (t, 1))) > - { > - tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p, > - is_gimple_val, fb_rvalue); > - ret = MIN (ret, tret); > - } > + tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p, > + is_gimple_val, fb_rvalue); > + ret = MIN (ret, tret); > + } > + else if (TREE_CODE (t) == COMPONENT_REF) > + { > + tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > + is_gimple_reg, fb_rvalue); > + ret = MIN (ret, tret); > } > > STRIP_USELESS_TYPE_CONVERSION (TREE_OPERAND (t, 0)); > @@ -6914,6 +6906,8 @@ gimplify_target_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p) > { > if (!TYPE_SIZES_GIMPLIFIED (TREE_TYPE (temp))) > gimplify_type_sizes (TREE_TYPE (temp), pre_p); > + /* FIXME: this is correct only when the size of the type does > + not depend on expressions evaluated in init. */ > gimplify_vla_decl (temp, pre_p); > } > else >
Am Montag, den 18.10.2021, 12:35 -0400 schrieb Jason Merrill: > On 10/17/21 09:52, Uecker, Martin wrote: > > > > Here is the 4th version of the patch. I tried to implement > > Jason's suggestion and this also fixes the problem. But > > I am not sure I understand the condition on > > the TREE_SIDE_EFFECTS ... > > Checking TREE_SIDE_EFFECTS filters out many trivial cases that we don't > need to worry about. Yes, but are we sure there are always side effects in the cases we care about? I assume that the problematic case are only those where the size expression depends on a variable and then there was a write to one.. But I am not sure. > I think we also want to check > variably_modified_type_p, which ought to avoid the OMP problem below. I don't think so because the problem below involves VM types. Martin > > And there is now another problem: > > > > c_finish_omp_for in c-family/c-omp.c does not seem > > to understand the expressions anymore and I get a test > > failure in > > > > testsuite/c-c++-common/gomp/for-5.c > > > > where I now get an "invalid increment expression" > > instead of the expected error. > > (bootstrapping and all other tests work fine) > > > > > > Martin > > > > > > > > > > Fix ICE when mixing VLAs and statement expressions [PR91038] > > > > When returning VM-types from statement expressions, this can > > lead to an ICE when declarations from the statement expression > > are referred to later. Most of these issues can be addressed by > > gimplifying the base expression earlier in gimplify_compound_lval. > > > > Another issue is fixed by adding SAVE_EXPRs in pointer_int_sum > > in the FE to force a correct order of evaluation. This fixes > > PR91038 and some of the test cases from PR29970 (structs with > > VLA members need further work). > > > > > > 2021-08-01 Martin Uecker <muecker@gwdg.de> > > > > 2021-08-01 Martin Uecker <muecker@gwdg.de> > > > > gcc/ > > PR c/91038 > > PR c/29970 > > > > * gimplify.c (gimplify_var_or_parm_decl): Update comment. > > (gimplify_compound_lval): > > Gimplify base expression first. > > (gimplify_target_expr): Add comment. > > * c-family/c- > > common.c (pointer_int_sum): Wrap pointer > > operand in SAVE_EXPR and also it to the integer > > argument. > > > > gcc/testsuite/ > > PR c/91038 > > PR c/29970 > > * gcc.dg/vla-stexp-3.c: > > New test. > > * gcc.dg/vla-stexp-4.c: New test. > > * gcc.dg/vla-stexp-5.c: New test. > > * > > gcc.dg/vla-stexp-6.c: New test. > > * gcc.dg/vla-stexp-7.c: New test. > > * gcc.dg/vla-stexp- > > 8.c: New test. > > * gcc.dg/vla-stexp-9.c: New test. > > > > > > diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c > > index 9d19e352725..522085664f5 100644 > > --- a/gcc/c-family/c-common.c > > +++ b/gcc/c-family/c-common.c > > @@ -3348,6 +3348,16 @@ pointer_int_sum (location_t loc, enum tree_code resultcode, > > intop = convert (c_common_type_for_size (TYPE_PRECISION (sizetype), > > TYPE_UNSIGNED (sizetype)), intop); > > > > + /* Wrap the pointer expression in a SAVE_EXPR to make sure it > > + * is evaluated first because the size expression may depend on it > > + * for VM types. > > + */ > > We usually don't give the trailing */ its own line. > > > + if (TREE_SIDE_EFFECTS (size_exp)) > > + { > > + ptrop = build1_loc (loc, SAVE_EXPR, TREE_TYPE (ptrop), ptrop); > > Why not use the save_expr function? > > > + intop = build2 (COMPOUND_EXPR, TREE_TYPE (intop), ptrop, intop); > > + } > > + > > /* Replace the integer argument with a suitable product by the object size. > > Do this multiplication as signed, then convert to the appropriate type > > for the pointer operation and disregard an overflow that occurred only > > diff --git a/gcc/gimplify.c b/gcc/gimplify.c > > index d8e4b139349..be5b00b6716 100644 > > --- a/gcc/gimplify.c > > +++ b/gcc/gimplify.c > > @@ -2958,7 +2958,10 @@ gimplify_var_or_parm_decl (tree *expr_p) > > declaration, for which we've already issued an error. It would > > be really nice if the front end wouldn't leak these at all. > > Currently the only known culprit is C++ destructors, as seen > > - in g++.old-deja/g++.jason/binding.C. */ > > + in g++.old-deja/g++.jason/binding.C. > > + Another possible culpit are size expressions for variably modified > > + types which are lost in the FE or not gimplified correctly. > > + */ > > As above. > > > if (VAR_P (decl) > > && !DECL_SEEN_IN_BIND_EXPR_P (decl) > > && !TREE_STATIC (decl) && !DECL_EXTERNAL (decl) > > @@ -3103,16 +3106,22 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq > > *post_p, > > expression until we deal with any variable bounds, sizes, or > > positions in order to deal with PLACEHOLDER_EXPRs. > > > > - So we do this in three steps. First we deal with the annotations > > - for any variables in the components, then we gimplify the base, > > - then we gimplify any indices, from left to right. */ > > + The base expression may contain a statement expression that > > + has declarations used in size expressions, so has to be > > + gimplified before gimplifying the size expressions. > > + > > + So we do this in three steps. First we deal with variable > > + bounds, sizes, and positions, then we gimplify the base, > > + then we deal with the annotations for any variables in the > > + components and any indices, from left to right. */ > > + > > for (i = expr_stack.length () - 1; i >= 0; i--) > > { > > tree t = expr_stack[i]; > > > > if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) > > { > > - /* Gimplify the low bound and element type size and put them into > > + /* Deal with the low bound and element type size and put them into > > the ARRAY_REF. If these values are set, they have already been > > gimplified. */ > > if (TREE_OPERAND (t, 2) == NULL_TREE) > > @@ -3121,18 +3130,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq > > *post_p, > > if (!is_gimple_min_invariant (low)) > > { > > TREE_OPERAND (t, 2) = low; > > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, > > - post_p, is_gimple_reg, > > - fb_rvalue); > > - ret = MIN (ret, tret); > > } > > } > > - else > > - { > > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > > - is_gimple_reg, fb_rvalue); > > - ret = MIN (ret, tret); > > - } > > > > if (TREE_OPERAND (t, 3) == NULL_TREE) > > { > > @@ -3149,18 +3148,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq > > *post_p, > > elmt_size, factor); > > > > TREE_OPERAND (t, 3) = elmt_size; > > - tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, > > - post_p, is_gimple_reg, > > - fb_rvalue); > > - ret = MIN (ret, tret); > > } > > } > > - else > > - { > > - tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p, > > - is_gimple_reg, fb_rvalue); > > - ret = MIN (ret, tret); > > - } > > } > > else if (TREE_CODE (t) == COMPONENT_REF) > > { > > @@ -3180,18 +3169,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq > > *post_p, > > offset, factor); > > > > TREE_OPERAND (t, 2) = offset; > > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, > > - post_p, is_gimple_reg, > > - fb_rvalue); > > - ret = MIN (ret, tret); > > } > > } > > - else > > - { > > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > > - is_gimple_reg, fb_rvalue); > > - ret = MIN (ret, tret); > > - } > > } > > } > > > > @@ -3202,21 +3181,34 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq > > *post_p, > > fallback | fb_lvalue); > > ret = MIN (ret, tret); > > > > - /* And finally, the indices and operands of ARRAY_REF. During this > > - loop we also remove any useless conversions. */ > > + /* Step 3: gimplify size expressions and the indices and operands of > > + ARRAY_REF. During this loop we also remove any useless conversions. */ > > + > > for (; expr_stack.length () > 0; ) > > { > > tree t = expr_stack.pop (); > > > > if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) > > { > > + /* Gimplify the low bound and element type size. */ > > + tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > > + is_gimple_reg, fb_rvalue); > > + ret = MIN (ret, tret); > > + > > + tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p, > > + is_gimple_reg, fb_rvalue); > > + ret = MIN (ret, tret); > > + > > /* Gimplify the dimension. */ > > - if (!is_gimple_min_invariant (TREE_OPERAND (t, 1))) > > - { > > - tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p, > > - is_gimple_val, fb_rvalue); > > - ret = MIN (ret, tret); > > - } > > + tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p, > > + is_gimple_val, fb_rvalue); > > + ret = MIN (ret, tret); > > + } > > + else if (TREE_CODE (t) == COMPONENT_REF) > > + { > > + tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > > + is_gimple_reg, fb_rvalue); > > + ret = MIN (ret, tret); > > } > > > > STRIP_USELESS_TYPE_CONVERSION (TREE_OPERAND (t, 0)); > > @@ -6914,6 +6906,8 @@ gimplify_target_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p) > > { > > if (!TYPE_SIZES_GIMPLIFIED (TREE_TYPE (temp))) > > gimplify_type_sizes (TREE_TYPE (temp), pre_p); > > + /* FIXME: this is correct only when the size of the type does > > + not depend on expressions evaluated in init. */ > > gimplify_vla_decl (temp, pre_p); > > } > > else > >
On 10/20/21 01:58, Uecker, Martin wrote: > Am Montag, den 18.10.2021, 12:35 -0400 schrieb Jason Merrill: >> On 10/17/21 09:52, Uecker, Martin wrote: >>> >>> Here is the 4th version of the patch. I tried to implement >>> Jason's suggestion and this also fixes the problem. But >>> I am not sure I understand the condition on >>> the TREE_SIDE_EFFECTS ... >> >> Checking TREE_SIDE_EFFECTS filters out many trivial cases that we don't >> need to worry about. > > Yes, but are we sure there are always side effects in the > cases we care about? I assume that the problematic case > are only those where the size expression depends on a > variable and then there was a write to one.. But I am not > sure. The problematic case should always involve a SAVE_EXPR or TARGET_EXPR, which has TREE_SIDE_EFFECTS. >> I think we also want to check >> variably_modified_type_p, which ought to avoid the OMP problem below. > > I don't think so because the problem below involves VM types. Ah, true. >>> And there is now another problem: >>> >>> c_finish_omp_for in c-family/c-omp.c does not seem >>> to understand the expressions anymore and I get a test >>> failure in >>> >>> testsuite/c-c++-common/gomp/for-5.c >>> >>> where I now get an "invalid increment expression" >>> instead of the expected error. >>> (bootstrapping and all other tests work fine) Ah, yes, because the variable size is still wrapped in a SAVE_EXPR even if the inner expression is just a variable reference. I think we only want to do this transformation if size_exp involves a BIND_EXPR. And probably do it sooner, changing size_exp rather than intop. Jason
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c index 9d19e352725..522085664f5 100644 --- a/gcc/c-family/c-common.c +++ b/gcc/c-family/c-common.c @@ -3348,6 +3348,16 @@ pointer_int_sum (location_t loc, enum tree_code resultcode, intop = convert (c_common_type_for_size (TYPE_PRECISION (sizetype), TYPE_UNSIGNED (sizetype)), intop); + /* Wrap the pointer expression in a SAVE_EXPR to make sure it + * is evaluated first because the size expression may depend on it + * for VM types. + */ + if (TREE_SIDE_EFFECTS (size_exp)) + { + ptrop = build1_loc (loc, SAVE_EXPR, TREE_TYPE (ptrop), ptrop); + intop = build2 (COMPOUND_EXPR, TREE_TYPE (intop), ptrop, intop); + } + /* Replace the integer argument with a suitable product by the object size. Do this multiplication as signed, then convert to the appropriate type for the pointer operation and disregard an overflow that occurred only diff --git a/gcc/gimplify.c b/gcc/gimplify.c index d8e4b139349..be5b00b6716 100644 --- a/gcc/gimplify.c +++ b/gcc/gimplify.c @@ -2958,7 +2958,10 @@ gimplify_var_or_parm_decl (tree *expr_p) declaration, for which we've already issued an error. It would be really nice if the front end wouldn't leak these at all. Currently the only known culprit is C++ destructors, as seen - in g++.old-deja/g++.jason/binding.C. */ + in g++.old-deja/g++.jason/binding.C. + Another possible culpit are size expressions for variably modified + types which are lost in the FE or not gimplified correctly. + */ if (VAR_P (decl) && !DECL_SEEN_IN_BIND_EXPR_P (decl) && !TREE_STATIC (decl) && !DECL_EXTERNAL (decl) @@ -3103,16 +3106,22 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p, expression until we deal with any variable bounds, sizes, or positions in order to deal with PLACEHOLDER_EXPRs. - So we do this in three steps. First we deal with the annotations - for any variables in the components, then we gimplify the base, - then we gimplify any indices, from left to right. */ + The base expression may contain a statement expression that + has declarations used in size expressions, so has to be + gimplified before gimplifying the size expressions. + + So we do this in three steps. First we deal with variable + bounds, sizes, and positions, then we gimplify the base, + then we deal with the annotations for any variables in the + components and any indices, from left to right. */ + for (i = expr_stack.length () - 1; i >= 0; i--) { tree t = expr_stack[i]; if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) { - /* Gimplify the low bound and element type size and put them into + /* Deal with the low bound and element type size and put them into the ARRAY_REF. If these values are set, they have already been gimplified. */ if (TREE_OPERAND (t, 2) == NULL_TREE) @@ -3121,18 +3130,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p, if (!is_gimple_min_invariant (low)) { TREE_OPERAND (t, 2) = low; - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, - post_p, is_gimple_reg, - fb_rvalue); - ret = MIN (ret, tret); } } - else - { - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, - is_gimple_reg, fb_rvalue); - ret = MIN (ret, tret); - } if (TREE_OPERAND (t, 3) == NULL_TREE) { @@ -3149,18 +3148,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p, elmt_size, factor); TREE_OPERAND (t, 3) = elmt_size; - tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, - post_p, is_gimple_reg, - fb_rvalue); - ret = MIN (ret, tret); } } - else - { - tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p, - is_gimple_reg, fb_rvalue); - ret = MIN (ret, tret); - } } else if (TREE_CODE (t) == COMPONENT_REF) { @@ -3180,18 +3169,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p, offset, factor); TREE_OPERAND (t, 2) = offset; - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, - post_p, is_gimple_reg, - fb_rvalue); - ret = MIN (ret, tret); } } - else - { - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, - is_gimple_reg, fb_rvalue); - ret = MIN (ret, tret); - } } } @@ -3202,21 +3181,34 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p, fallback | fb_lvalue); ret = MIN (ret, tret); - /* And finally, the indices and operands of ARRAY_REF. During this - loop we also remove any useless conversions. */ + /* Step 3: gimplify size expressions and the indices and operands of + ARRAY_REF. During this loop we also remove any useless conversions. */ + for (; expr_stack.length () > 0; ) { tree t = expr_stack.pop (); if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) { + /* Gimplify the low bound and element type size. */ + tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, + is_gimple_reg, fb_rvalue); + ret = MIN (ret, tret); + + tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p, + is_gimple_reg, fb_rvalue); + ret = MIN (ret, tret); + /* Gimplify the dimension. */ - if (!is_gimple_min_invariant (TREE_OPERAND (t, 1))) - { - tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p, - is_gimple_val, fb_rvalue); - ret = MIN (ret, tret); - } + tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p, + is_gimple_val, fb_rvalue); + ret = MIN (ret, tret); + } + else if (TREE_CODE (t) == COMPONENT_REF) + { + tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, + is_gimple_reg, fb_rvalue); + ret = MIN (ret, tret); } STRIP_USELESS_TYPE_CONVERSION (TREE_OPERAND (t, 0)); @@ -6914,6 +6906,8 @@ gimplify_target_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p) { if (!TYPE_SIZES_GIMPLIFIED (TREE_TYPE (temp))) gimplify_type_sizes (TREE_TYPE (temp), pre_p); + /* FIXME: this is correct only when the size of the type does + not depend on expressions evaluated in init. */ gimplify_vla_decl (temp, pre_p); } else
Here is the 4th version of the patch. I tried to implement Jason's suggestion and this also fixes the problem. But I am not sure I understand the condition on the TREE_SIDE_EFFECTS ... And there is now another problem: c_finish_omp_for in c-family/c-omp.c does not seem to understand the expressions anymore and I get a test failure in testsuite/c-c++-common/gomp/for-5.c where I now get an "invalid increment expression" instead of the expected error. (bootstrapping and all other tests work fine) Martin Fix ICE when mixing VLAs and statement expressions [PR91038] When returning VM-types from statement expressions, this can lead to an ICE when declarations from the statement expression are referred to later. Most of these issues can be addressed by gimplifying the base expression earlier in gimplify_compound_lval. Another issue is fixed by adding SAVE_EXPRs in pointer_int_sum in the FE to force a correct order of evaluation. This fixes PR91038 and some of the test cases from PR29970 (structs with VLA members need further work). 2021-08-01 Martin Uecker <muecker@gwdg.de> 2021-08-01 Martin Uecker <muecker@gwdg.de> gcc/ PR c/91038 PR c/29970 * gimplify.c (gimplify_var_or_parm_decl): Update comment. (gimplify_compound_lval): Gimplify base expression first. (gimplify_target_expr): Add comment. * c-family/c- common.c (pointer_int_sum): Wrap pointer operand in SAVE_EXPR and also it to the integer argument. gcc/testsuite/ PR c/91038 PR c/29970 * gcc.dg/vla-stexp-3.c: New test. * gcc.dg/vla-stexp-4.c: New test. * gcc.dg/vla-stexp-5.c: New test. * gcc.dg/vla-stexp-6.c: New test. * gcc.dg/vla-stexp-7.c: New test. * gcc.dg/vla-stexp- 8.c: New test. * gcc.dg/vla-stexp-9.c: New test.