| Message ID | 20140109182202.GJ892@tucnak.redhat.com |
|---|---|
| State | New |
| Headers | show |
Jakub Jelinek <jakub@redhat.com> wrote: >Hi! > >As discussed in the PR, if a var isn't addressable and has gimple reg >type, >I don't see any point to honor it's DECL_ALIGN, we only refer to the >var through SSA_NAME_VAR of SSA_NAMEs, nothing is allocated on the >stack >immediately and the SSA_NAMEs are turned into pseudos for which we only >care >about their modes and corresponding alignments if they need to be >spilled to >stack. > >Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? Ok. Thanks, Richard. >2014-01-09 Jakub Jelinek <jakub@redhat.com> > > PR middle-end/47735 > * cfgexpand.c (expand_one_var): For SSA_NAMEs, if the underlying > var satisfies use_register_for_decl, just take into account type > alignment, rather than decl alignment. > > * gcc.target/i386/pr47735.c: New test. > >--- gcc/cfgexpand.c.jj 2014-01-08 19:37:33.630986939 +0100 >+++ gcc/cfgexpand.c 2014-01-09 13:38:45.073324129 +0100 >@@ -1215,8 +1215,11 @@ expand_one_var (tree var, bool toplevel, > we conservatively assume it will be on stack even if VAR is > eventually put into register after RA pass. For non-automatic > variables, which won't be on stack, we collect alignment of >- type and ignore user specified alignment. */ >- if (TREE_STATIC (var) || DECL_EXTERNAL (var)) >+ type and ignore user specified alignment. Similarly for >+ SSA_NAMEs for which use_register_for_decl returns true. */ >+ if (TREE_STATIC (var) >+ || DECL_EXTERNAL (var) >+ || (TREE_CODE (origvar) == SSA_NAME && use_register_for_decl >(var))) > align = MINIMUM_ALIGNMENT (TREE_TYPE (var), > TYPE_MODE (TREE_TYPE (var)), > TYPE_ALIGN (TREE_TYPE (var))); >--- gcc/testsuite/gcc.target/i386/pr47735.c.jj 2014-01-09 >13:30:14.410941107 +0100 >+++ gcc/testsuite/gcc.target/i386/pr47735.c 2014-01-09 >13:28:45.000000000 +0100 >@@ -0,0 +1,16 @@ >+/* PR middle-end/47735 */ >+/* { dg-do compile } */ >+/* { dg-options "-O2 -fomit-frame-pointer" } */ >+ >+unsigned >+mulh (unsigned a, unsigned b) >+{ >+ unsigned long long l __attribute__ ((aligned (32))) >+ = ((unsigned long long) a * (unsigned long long) b) >> 32; >+ return l; >+} >+ >+/* No need to dynamically realign the stack here. */ >+/* { dg-final { scan-assembler-not "and\[^\n\r]*%\[re\]sp" } } */ >+/* Nor use a frame pointer. */ >+/* { dg-final { scan-assembler-not "%\[re\]bp" } } */ > > Jakub
--- gcc/cfgexpand.c.jj 2014-01-08 19:37:33.630986939 +0100 +++ gcc/cfgexpand.c 2014-01-09 13:38:45.073324129 +0100 @@ -1215,8 +1215,11 @@ expand_one_var (tree var, bool toplevel, we conservatively assume it will be on stack even if VAR is eventually put into register after RA pass. For non-automatic variables, which won't be on stack, we collect alignment of - type and ignore user specified alignment. */ - if (TREE_STATIC (var) || DECL_EXTERNAL (var)) + type and ignore user specified alignment. Similarly for + SSA_NAMEs for which use_register_for_decl returns true. */ + if (TREE_STATIC (var) + || DECL_EXTERNAL (var) + || (TREE_CODE (origvar) == SSA_NAME && use_register_for_decl (var))) align = MINIMUM_ALIGNMENT (TREE_TYPE (var), TYPE_MODE (TREE_TYPE (var)), TYPE_ALIGN (TREE_TYPE (var))); --- gcc/testsuite/gcc.target/i386/pr47735.c.jj 2014-01-09 13:30:14.410941107 +0100 +++ gcc/testsuite/gcc.target/i386/pr47735.c 2014-01-09 13:28:45.000000000 +0100 @@ -0,0 +1,16 @@ +/* PR middle-end/47735 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fomit-frame-pointer" } */ + +unsigned +mulh (unsigned a, unsigned b) +{ + unsigned long long l __attribute__ ((aligned (32))) + = ((unsigned long long) a * (unsigned long long) b) >> 32; + return l; +} + +/* No need to dynamically realign the stack here. */ +/* { dg-final { scan-assembler-not "and\[^\n\r]*%\[re\]sp" } } */ +/* Nor use a frame pointer. */ +/* { dg-final { scan-assembler-not "%\[re\]bp" } } */