| Message ID | 20140505202703.GR11802@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Mon, May 05, 2014 at 10:27:03PM +0200, Marek Polacek wrote: > In this PR the issue is that we reject (valid) code such as > _Alignas (long long) long long foo; > with -m32, because we trip this condition: > > alignas_align = 1U << declspecs->align_log; > if (alignas_align < TYPE_ALIGN_UNIT (type)) > { > if (name) > error_at (loc, "%<_Alignas%> specifiers cannot reduce " > "alignment of %qE", name); > > and error later on, since alignas_align is 4 (correct, see PR52023 for > why), but TYPE_ALIGN_UNIT of long long is 8. I think TYPE_ALIGN_UNIT > is wrong here as that won't give us minimal alignment required. > In c_sizeof_or_alignof_type we already have the code to compute such > minimal alignment so I just moved the code to a separate function > and used that instead of TYPE_ALIGN_UNIT. > > Note that the test is run only on i?86 and x86_64, because we can't (?) > easily determine which target requires what alignment. > > Regtested/bootstrapped on x86_64-unknown-linux-gnu and > powerpc64-unknown-linux-gnu, ok for trunk? I should add that I checked what clang does on my testcase, and with this patch both compilers accept and reject the same sort of testcases, both with -m32 and -m64. Marek
On Mon, May 5, 2014 at 10:27 PM, Marek Polacek <polacek@redhat.com> wrote: > In this PR the issue is that we reject (valid) code such as > _Alignas (long long) long long foo; > with -m32, because we trip this condition: > > alignas_align = 1U << declspecs->align_log; > if (alignas_align < TYPE_ALIGN_UNIT (type)) > { > if (name) > error_at (loc, "%<_Alignas%> specifiers cannot reduce " > "alignment of %qE", name); > > and error later on, since alignas_align is 4 (correct, see PR52023 for > why), but TYPE_ALIGN_UNIT of long long is 8. I think TYPE_ALIGN_UNIT > is wrong here as that won't give us minimal alignment required. > In c_sizeof_or_alignof_type we already have the code to compute such > minimal alignment so I just moved the code to a separate function > and used that instead of TYPE_ALIGN_UNIT. Hmm, but isn't TYPE_ALIGN_UNIT wrong then? Richard. > > Note that the test is run only on i?86 and x86_64, because we can't (?) > easily determine which target requires what alignment. > > Regtested/bootstrapped on x86_64-unknown-linux-gnu and > powerpc64-unknown-linux-gnu, ok for trunk? > > 2014-05-05 Marek Polacek <polacek@redhat.com> > > PR c/61053 > c-family/ > * c-common.c (min_align_of_type): New function factored out from... > (c_sizeof_or_alignof_type): ...here. > * c-common.h (min_align_of_type): Declare. > c/ > * c-decl.c (grokdeclarator): Use min_align_of_type instead of > TYPE_ALIGN_UNIT. > testsuite/ > * gcc.dg/pr61053.c: New test. > > diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c > index 0ad955d..6d4440e 100644 > --- gcc/c-family/c-common.c > +++ gcc/c-family/c-common.c > @@ -4931,6 +4931,26 @@ c_common_get_alias_set (tree t) > return -1; > } > > +/* Return the least alignment required for type TYPE. */ > + > +unsigned int > +min_align_of_type (tree type) > +{ > + unsigned int align = TYPE_ALIGN (type); > + align = MIN (align, BIGGEST_ALIGNMENT); > +#ifdef BIGGEST_FIELD_ALIGNMENT > + align = MIN (align, BIGGEST_FIELD_ALIGNMENT); > +#endif > + unsigned int field_align = align; > +#ifdef ADJUST_FIELD_ALIGN > + tree field = build_decl (UNKNOWN_LOCATION, FIELD_DECL, NULL_TREE, > + type); > + field_align = ADJUST_FIELD_ALIGN (field, field_align); > +#endif > + align = MIN (align, field_align); > + return align / BITS_PER_UNIT; > +} > + > /* Compute the value of 'sizeof (TYPE)' or '__alignof__ (TYPE)', where > the IS_SIZEOF parameter indicates which operator is being applied. > The COMPLAIN flag controls whether we should diagnose possibly > @@ -5009,21 +5029,7 @@ c_sizeof_or_alignof_type (location_t loc, > size_int (TYPE_PRECISION (char_type_node) > / BITS_PER_UNIT)); > else if (min_alignof) > - { > - unsigned int align = TYPE_ALIGN (type); > - align = MIN (align, BIGGEST_ALIGNMENT); > -#ifdef BIGGEST_FIELD_ALIGNMENT > - align = MIN (align, BIGGEST_FIELD_ALIGNMENT); > -#endif > - unsigned int field_align = align; > -#ifdef ADJUST_FIELD_ALIGN > - tree field = build_decl (UNKNOWN_LOCATION, FIELD_DECL, NULL_TREE, > - type); > - field_align = ADJUST_FIELD_ALIGN (field, field_align); > -#endif > - align = MIN (align, field_align); > - value = size_int (align / BITS_PER_UNIT); > - } > + value = size_int (min_align_of_type (type)); > else > value = size_int (TYPE_ALIGN_UNIT (type)); > } > diff --git gcc/c-family/c-common.h gcc/c-family/c-common.h > index 57b7dce..d34d2bb 100644 > --- gcc/c-family/c-common.h > +++ gcc/c-family/c-common.h > @@ -758,6 +758,7 @@ extern tree c_wrap_maybe_const (tree, bool); > extern tree c_save_expr (tree); > extern tree c_common_truthvalue_conversion (location_t, tree); > extern void c_apply_type_quals_to_decl (int, tree); > +extern unsigned int min_align_of_type (tree); > extern tree c_sizeof_or_alignof_type (location_t, tree, bool, bool, int); > extern tree c_alignof_expr (location_t, tree); > /* Print an error message for invalid operands to arith operation CODE. > diff --git gcc/c/c-decl.c gcc/c/c-decl.c > index 6e7c589..9f7419a 100644 > --- gcc/c/c-decl.c > +++ gcc/c/c-decl.c > @@ -5931,7 +5931,7 @@ grokdeclarator (const struct c_declarator *declarator, > else if (declspecs->align_log != -1) > { > alignas_align = 1U << declspecs->align_log; > - if (alignas_align < TYPE_ALIGN_UNIT (type)) > + if (alignas_align < min_align_of_type (type)) > { > if (name) > error_at (loc, "%<_Alignas%> specifiers cannot reduce " > diff --git gcc/testsuite/gcc.dg/pr61053.c gcc/testsuite/gcc.dg/pr61053.c > index e69de29..e3db534 100644 > --- gcc/testsuite/gcc.dg/pr61053.c > +++ gcc/testsuite/gcc.dg/pr61053.c > @@ -0,0 +1,75 @@ > +/* PR c/61053 */ > +/* { dg-do compile { target i?86-*-* x86_64-*-* } } */ > +/* { dg-options "-std=c11 -pedantic-errors" } */ > + > +_Alignas (char) char cc; > +_Alignas (short int) char cs; > +_Alignas (int) char ci; > +_Alignas (long int) char cl; > +_Alignas (long long int) char cll; > +_Alignas (float) char cf; > +_Alignas (double) char cd; > +_Alignas (long double) char cld; > + > +_Alignas (char) short int sc; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (short int) short int ss; > +_Alignas (int) short int si; > +_Alignas (long int) short int sl; > +_Alignas (long long int) short int sll; > +_Alignas (float) short int sf; > +_Alignas (double) short int sd; > +_Alignas (long double) short int sld; > + > +_Alignas (char) int ic; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (short int) int is; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (int) int ii; > +_Alignas (long int) int il; > +_Alignas (long long int) int ill; > +_Alignas (float) int if_; > +_Alignas (double) int id; > +_Alignas (long double) int ild; > + > +_Alignas (char) long int lic; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (short int) long int lis; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (int) long int lii; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (long int) long int lil; > +_Alignas (long long int) long int lill; > +_Alignas (float) long int lif; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (double) long int lid; > +_Alignas (long double) long int lild; > + > +_Alignas (char) long long int llic; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (short int) long long int llis; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (int) long long int llii; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (long int) long long int llil; > +_Alignas (long long int) long long int llill; > +_Alignas (float) long long int llif; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (double) long long int llid; > +_Alignas (long double) long long int llild; > + > +_Alignas (char) float fc; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (short int) float fs; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (int) float fi; > +_Alignas (long int) float fl; > +_Alignas (long long int) float fll; > +_Alignas (float) float ff; > +_Alignas (double) float fd; > +_Alignas (long double) float fld; > + > +_Alignas (char) double dc; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (short int) double ds; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (int) double di; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (long int) double dl; > +_Alignas (long long int) double dll; > +_Alignas (float) double df; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (double) double dd; > +_Alignas (long double) double dld; > + > +_Alignas (char) long double ldc; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (short int) long double lds; /* { dg-error "cannot reduce alignment" } */ > +_Alignas (int) long double ldi; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (long int) long double ldl; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (long long int) long double ldll; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (float) long double ldf; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (double) long double ldd; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ > +_Alignas (long double) long double ldld; > > Marek
On Tue, May 06, 2014 at 10:04:33AM +0200, Richard Biener wrote: > On Mon, May 5, 2014 at 10:27 PM, Marek Polacek <polacek@redhat.com> wrote: > > In this PR the issue is that we reject (valid) code such as > > _Alignas (long long) long long foo; > > with -m32, because we trip this condition: > > > > alignas_align = 1U << declspecs->align_log; > > if (alignas_align < TYPE_ALIGN_UNIT (type)) > > { > > if (name) > > error_at (loc, "%<_Alignas%> specifiers cannot reduce " > > "alignment of %qE", name); > > > > and error later on, since alignas_align is 4 (correct, see PR52023 for > > why), but TYPE_ALIGN_UNIT of long long is 8. I think TYPE_ALIGN_UNIT > > is wrong here as that won't give us minimal alignment required. > > In c_sizeof_or_alignof_type we already have the code to compute such > > minimal alignment so I just moved the code to a separate function > > and used that instead of TYPE_ALIGN_UNIT. > > Hmm, but isn't TYPE_ALIGN_UNIT wrong then? No, after all, you don't want to change __alignof__ (long long), that is pretty essential part of ABI. Jakub
On Tue, May 06, 2014 at 10:14:42AM +0200, Jakub Jelinek wrote: > > Hmm, but isn't TYPE_ALIGN_UNIT wrong then? > > No, after all, you don't want to change __alignof__ (long long), that is > pretty essential part of ABI. Yeah, as I understand things, for x86_64 __alignof__ (T) returns *preferred* alignment which is specified for each type in the ABI (Figure 3.1: Scalar Types), and is the same as sizeof (T). But _Alignof (T) (thus also _Alignas (T)) is the *least* alignment for a type -- and they can differ if the type is in a struct/union. Please correct me if I'm mistaken. Marek
On Mon, 5 May 2014, Marek Polacek wrote: > In this PR the issue is that we reject (valid) code such as > _Alignas (long long) long long foo; > with -m32, because we trip this condition: > > alignas_align = 1U << declspecs->align_log; > if (alignas_align < TYPE_ALIGN_UNIT (type)) > { > if (name) > error_at (loc, "%<_Alignas%> specifiers cannot reduce " > "alignment of %qE", name); > > and error later on, since alignas_align is 4 (correct, see PR52023 for > why), but TYPE_ALIGN_UNIT of long long is 8. I think TYPE_ALIGN_UNIT > is wrong here as that won't give us minimal alignment required. > In c_sizeof_or_alignof_type we already have the code to compute such > minimal alignment so I just moved the code to a separate function > and used that instead of TYPE_ALIGN_UNIT. > > Note that the test is run only on i?86 and x86_64, because we can't (?) > easily determine which target requires what alignment. > > Regtested/bootstrapped on x86_64-unknown-linux-gnu and > powerpc64-unknown-linux-gnu, ok for trunk? OK, though I'm not sure if the "lp64" conditions are right in the testcase (i.e. if x32 has the same peculiarity as -m32 here, which is what's implied by the use of "lp64").
On Wed, May 7, 2014 at 10:15 AM, Joseph S. Myers <joseph@codesourcery.com> wrote: > On Mon, 5 May 2014, Marek Polacek wrote: > >> In this PR the issue is that we reject (valid) code such as >> _Alignas (long long) long long foo; >> with -m32, because we trip this condition: >> >> alignas_align = 1U << declspecs->align_log; >> if (alignas_align < TYPE_ALIGN_UNIT (type)) >> { >> if (name) >> error_at (loc, "%<_Alignas%> specifiers cannot reduce " >> "alignment of %qE", name); >> >> and error later on, since alignas_align is 4 (correct, see PR52023 for >> why), but TYPE_ALIGN_UNIT of long long is 8. I think TYPE_ALIGN_UNIT >> is wrong here as that won't give us minimal alignment required. >> In c_sizeof_or_alignof_type we already have the code to compute such >> minimal alignment so I just moved the code to a separate function >> and used that instead of TYPE_ALIGN_UNIT. >> >> Note that the test is run only on i?86 and x86_64, because we can't (?) >> easily determine which target requires what alignment. >> >> Regtested/bootstrapped on x86_64-unknown-linux-gnu and >> powerpc64-unknown-linux-gnu, ok for trunk? > > OK, though I'm not sure if the "lp64" conditions are right in the testcase It should be !ia32 instead of lp64. > (i.e. if x32 has the same peculiarity as -m32 here, which is what's > implied by the use of "lp64"). > Alignments of long long and long double on x32 are the same as x86-64.
On Wed, May 07, 2014 at 11:31:38AM -0700, H.J. Lu wrote: > > OK, though I'm not sure if the "lp64" conditions are right in the testcase > > It should be !ia32 instead of lp64. Ok, I changed lp64 to ! { ia32 } and committed the patch now. Marek
On Mon, May 05, 2014 at 10:27:03PM +0200, Marek Polacek wrote: > In this PR the issue is that we reject (valid) code such as > _Alignas (long long) long long foo; > with -m32, because we trip this condition: > > alignas_align = 1U << declspecs->align_log; > if (alignas_align < TYPE_ALIGN_UNIT (type)) > { > if (name) > error_at (loc, "%<_Alignas%> specifiers cannot reduce " > "alignment of %qE", name); > > and error later on, since alignas_align is 4 (correct, see PR52023 for > why), but TYPE_ALIGN_UNIT of long long is 8. I think TYPE_ALIGN_UNIT > is wrong here as that won't give us minimal alignment required. > In c_sizeof_or_alignof_type we already have the code to compute such > minimal alignment so I just moved the code to a separate function > and used that instead of TYPE_ALIGN_UNIT. > > Note that the test is run only on i?86 and x86_64, because we can't (?) > easily determine which target requires what alignment. > > Regtested/bootstrapped on x86_64-unknown-linux-gnu and > powerpc64-unknown-linux-gnu, ok for trunk? Can I backport this one to 4.9? Marek
Ping. On Sun, May 25, 2014 at 11:30:51AM +0200, Marek Polacek wrote: > On Mon, May 05, 2014 at 10:27:03PM +0200, Marek Polacek wrote: > > In this PR the issue is that we reject (valid) code such as > > _Alignas (long long) long long foo; > > with -m32, because we trip this condition: > > > > alignas_align = 1U << declspecs->align_log; > > if (alignas_align < TYPE_ALIGN_UNIT (type)) > > { > > if (name) > > error_at (loc, "%<_Alignas%> specifiers cannot reduce " > > "alignment of %qE", name); > > > > and error later on, since alignas_align is 4 (correct, see PR52023 for > > why), but TYPE_ALIGN_UNIT of long long is 8. I think TYPE_ALIGN_UNIT > > is wrong here as that won't give us minimal alignment required. > > In c_sizeof_or_alignof_type we already have the code to compute such > > minimal alignment so I just moved the code to a separate function > > and used that instead of TYPE_ALIGN_UNIT. > > > > Note that the test is run only on i?86 and x86_64, because we can't (?) > > easily determine which target requires what alignment. > > > > Regtested/bootstrapped on x86_64-unknown-linux-gnu and > > powerpc64-unknown-linux-gnu, ok for trunk? > > Can I backport this one to 4.9? Marek
On 06/02/14 00:52, Marek Polacek wrote: > Ping. > > On Sun, May 25, 2014 at 11:30:51AM +0200, Marek Polacek wrote: >> On Mon, May 05, 2014 at 10:27:03PM +0200, Marek Polacek wrote: >>> In this PR the issue is that we reject (valid) code such as >>> _Alignas (long long) long long foo; >>> with -m32, because we trip this condition: >>> >>> alignas_align = 1U << declspecs->align_log; >>> if (alignas_align < TYPE_ALIGN_UNIT (type)) >>> { >>> if (name) >>> error_at (loc, "%<_Alignas%> specifiers cannot reduce " >>> "alignment of %qE", name); >>> >>> and error later on, since alignas_align is 4 (correct, see PR52023 for >>> why), but TYPE_ALIGN_UNIT of long long is 8. I think TYPE_ALIGN_UNIT >>> is wrong here as that won't give us minimal alignment required. >>> In c_sizeof_or_alignof_type we already have the code to compute such >>> minimal alignment so I just moved the code to a separate function >>> and used that instead of TYPE_ALIGN_UNIT. >>> >>> Note that the test is run only on i?86 and x86_64, because we can't (?) >>> easily determine which target requires what alignment. >>> >>> Regtested/bootstrapped on x86_64-unknown-linux-gnu and >>> powerpc64-unknown-linux-gnu, ok for trunk? >> >> Can I backport this one to 4.9? Yes, backporting to 4.9 is fine. jeff
diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c index 0ad955d..6d4440e 100644 --- gcc/c-family/c-common.c +++ gcc/c-family/c-common.c @@ -4931,6 +4931,26 @@ c_common_get_alias_set (tree t) return -1; } +/* Return the least alignment required for type TYPE. */ + +unsigned int +min_align_of_type (tree type) +{ + unsigned int align = TYPE_ALIGN (type); + align = MIN (align, BIGGEST_ALIGNMENT); +#ifdef BIGGEST_FIELD_ALIGNMENT + align = MIN (align, BIGGEST_FIELD_ALIGNMENT); +#endif + unsigned int field_align = align; +#ifdef ADJUST_FIELD_ALIGN + tree field = build_decl (UNKNOWN_LOCATION, FIELD_DECL, NULL_TREE, + type); + field_align = ADJUST_FIELD_ALIGN (field, field_align); +#endif + align = MIN (align, field_align); + return align / BITS_PER_UNIT; +} + /* Compute the value of 'sizeof (TYPE)' or '__alignof__ (TYPE)', where the IS_SIZEOF parameter indicates which operator is being applied. The COMPLAIN flag controls whether we should diagnose possibly @@ -5009,21 +5029,7 @@ c_sizeof_or_alignof_type (location_t loc, size_int (TYPE_PRECISION (char_type_node) / BITS_PER_UNIT)); else if (min_alignof) - { - unsigned int align = TYPE_ALIGN (type); - align = MIN (align, BIGGEST_ALIGNMENT); -#ifdef BIGGEST_FIELD_ALIGNMENT - align = MIN (align, BIGGEST_FIELD_ALIGNMENT); -#endif - unsigned int field_align = align; -#ifdef ADJUST_FIELD_ALIGN - tree field = build_decl (UNKNOWN_LOCATION, FIELD_DECL, NULL_TREE, - type); - field_align = ADJUST_FIELD_ALIGN (field, field_align); -#endif - align = MIN (align, field_align); - value = size_int (align / BITS_PER_UNIT); - } + value = size_int (min_align_of_type (type)); else value = size_int (TYPE_ALIGN_UNIT (type)); } diff --git gcc/c-family/c-common.h gcc/c-family/c-common.h index 57b7dce..d34d2bb 100644 --- gcc/c-family/c-common.h +++ gcc/c-family/c-common.h @@ -758,6 +758,7 @@ extern tree c_wrap_maybe_const (tree, bool); extern tree c_save_expr (tree); extern tree c_common_truthvalue_conversion (location_t, tree); extern void c_apply_type_quals_to_decl (int, tree); +extern unsigned int min_align_of_type (tree); extern tree c_sizeof_or_alignof_type (location_t, tree, bool, bool, int); extern tree c_alignof_expr (location_t, tree); /* Print an error message for invalid operands to arith operation CODE. diff --git gcc/c/c-decl.c gcc/c/c-decl.c index 6e7c589..9f7419a 100644 --- gcc/c/c-decl.c +++ gcc/c/c-decl.c @@ -5931,7 +5931,7 @@ grokdeclarator (const struct c_declarator *declarator, else if (declspecs->align_log != -1) { alignas_align = 1U << declspecs->align_log; - if (alignas_align < TYPE_ALIGN_UNIT (type)) + if (alignas_align < min_align_of_type (type)) { if (name) error_at (loc, "%<_Alignas%> specifiers cannot reduce " diff --git gcc/testsuite/gcc.dg/pr61053.c gcc/testsuite/gcc.dg/pr61053.c index e69de29..e3db534 100644 --- gcc/testsuite/gcc.dg/pr61053.c +++ gcc/testsuite/gcc.dg/pr61053.c @@ -0,0 +1,75 @@ +/* PR c/61053 */ +/* { dg-do compile { target i?86-*-* x86_64-*-* } } */ +/* { dg-options "-std=c11 -pedantic-errors" } */ + +_Alignas (char) char cc; +_Alignas (short int) char cs; +_Alignas (int) char ci; +_Alignas (long int) char cl; +_Alignas (long long int) char cll; +_Alignas (float) char cf; +_Alignas (double) char cd; +_Alignas (long double) char cld; + +_Alignas (char) short int sc; /* { dg-error "cannot reduce alignment" } */ +_Alignas (short int) short int ss; +_Alignas (int) short int si; +_Alignas (long int) short int sl; +_Alignas (long long int) short int sll; +_Alignas (float) short int sf; +_Alignas (double) short int sd; +_Alignas (long double) short int sld; + +_Alignas (char) int ic; /* { dg-error "cannot reduce alignment" } */ +_Alignas (short int) int is; /* { dg-error "cannot reduce alignment" } */ +_Alignas (int) int ii; +_Alignas (long int) int il; +_Alignas (long long int) int ill; +_Alignas (float) int if_; +_Alignas (double) int id; +_Alignas (long double) int ild; + +_Alignas (char) long int lic; /* { dg-error "cannot reduce alignment" } */ +_Alignas (short int) long int lis; /* { dg-error "cannot reduce alignment" } */ +_Alignas (int) long int lii; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (long int) long int lil; +_Alignas (long long int) long int lill; +_Alignas (float) long int lif; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (double) long int lid; +_Alignas (long double) long int lild; + +_Alignas (char) long long int llic; /* { dg-error "cannot reduce alignment" } */ +_Alignas (short int) long long int llis; /* { dg-error "cannot reduce alignment" } */ +_Alignas (int) long long int llii; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (long int) long long int llil; +_Alignas (long long int) long long int llill; +_Alignas (float) long long int llif; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (double) long long int llid; +_Alignas (long double) long long int llild; + +_Alignas (char) float fc; /* { dg-error "cannot reduce alignment" } */ +_Alignas (short int) float fs; /* { dg-error "cannot reduce alignment" } */ +_Alignas (int) float fi; +_Alignas (long int) float fl; +_Alignas (long long int) float fll; +_Alignas (float) float ff; +_Alignas (double) float fd; +_Alignas (long double) float fld; + +_Alignas (char) double dc; /* { dg-error "cannot reduce alignment" } */ +_Alignas (short int) double ds; /* { dg-error "cannot reduce alignment" } */ +_Alignas (int) double di; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (long int) double dl; +_Alignas (long long int) double dll; +_Alignas (float) double df; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (double) double dd; +_Alignas (long double) double dld; + +_Alignas (char) long double ldc; /* { dg-error "cannot reduce alignment" } */ +_Alignas (short int) long double lds; /* { dg-error "cannot reduce alignment" } */ +_Alignas (int) long double ldi; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (long int) long double ldl; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (long long int) long double ldll; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (float) long double ldf; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (double) long double ldd; /* { dg-error "cannot reduce alignment" "" { target { lp64 } } } */ +_Alignas (long double) long double ldld;
In this PR the issue is that we reject (valid) code such as _Alignas (long long) long long foo; with -m32, because we trip this condition: alignas_align = 1U << declspecs->align_log; if (alignas_align < TYPE_ALIGN_UNIT (type)) { if (name) error_at (loc, "%<_Alignas%> specifiers cannot reduce " "alignment of %qE", name); and error later on, since alignas_align is 4 (correct, see PR52023 for why), but TYPE_ALIGN_UNIT of long long is 8. I think TYPE_ALIGN_UNIT is wrong here as that won't give us minimal alignment required. In c_sizeof_or_alignof_type we already have the code to compute such minimal alignment so I just moved the code to a separate function and used that instead of TYPE_ALIGN_UNIT. Note that the test is run only on i?86 and x86_64, because we can't (?) easily determine which target requires what alignment. Regtested/bootstrapped on x86_64-unknown-linux-gnu and powerpc64-unknown-linux-gnu, ok for trunk? 2014-05-05 Marek Polacek <polacek@redhat.com> PR c/61053 c-family/ * c-common.c (min_align_of_type): New function factored out from... (c_sizeof_or_alignof_type): ...here. * c-common.h (min_align_of_type): Declare. c/ * c-decl.c (grokdeclarator): Use min_align_of_type instead of TYPE_ALIGN_UNIT. testsuite/ * gcc.dg/pr61053.c: New test. Marek