On 10/12/2011 10:13 AM, Tom de Vries wrote: > On 10/10/2011 05:50 PM, Eric Botcazou wrote: >>> So, the patch for build_constant_desc does not have the desired effect. >> >> OK, too bad that we need to play this back-and-forth game with MEMs. So the >> original patch is OK (with TREE_READONLY (base) on the next line to mimic >> what >> is done just above and without the gcc/ prefix in the ChangeLog). If you >> have >> some available cycles, you can test and install the build_constant_desc >> change >> in the same commit, otherwise I'll do it myself. >> > > I'll include the build_constant_desc change in a bootstrap/reg-test on x86_64. > > Thanks, > - Tom
No problems found in bootstrap/reg-test on x86_64. Committed. Thanks, - Tom 2011-10-13 Tom de Vries <t...@codesourcery.com> * emit-rtl.c (set_mem_attributes_minus_bitpos): Set MEM_READONLY_P for static const strings. * varasm.c (build_constant_desc): Generate the memory location of the constant using gen_const_mem. * gcc.dg/memcpy-4.c: New test.
Index: gcc/emit-rtl.c =================================================================== --- gcc/emit-rtl.c (revision 179773) +++ gcc/emit-rtl.c (working copy) @@ -1696,6 +1696,12 @@ set_mem_attributes_minus_bitpos (rtx ref && !TREE_THIS_VOLATILE (base)) MEM_READONLY_P (ref) = 1; + /* Mark static const strings readonly as well. */ + if (base && TREE_CODE (base) == STRING_CST + && TREE_READONLY (base) + && TREE_STATIC (base)) + MEM_READONLY_P (ref) = 1; + /* 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 (t)) Index: gcc/varasm.c =================================================================== --- gcc/varasm.c (revision 179773) +++ gcc/varasm.c (working copy) @@ -3119,7 +3119,7 @@ build_constant_desc (tree exp) SET_SYMBOL_REF_DECL (symbol, decl); TREE_CONSTANT_POOL_ADDRESS_P (symbol) = 1; - rtl = gen_rtx_MEM (TYPE_MODE (TREE_TYPE (exp)), symbol); + rtl = gen_const_mem (TYPE_MODE (TREE_TYPE (exp)), symbol); set_mem_attributes (rtl, exp, 1); set_mem_alias_set (rtl, 0); set_mem_alias_set (rtl, const_alias_set); Index: gcc/testsuite/gcc.dg/memcpy-4.c =================================================================== --- /dev/null (new file) +++ gcc/testsuite/gcc.dg/memcpy-4.c (revision 0) @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-rtl-expand" } */ + +void +f1 (char *p) +{ + __builtin_memcpy (p, "123", 3); +} + +/* { dg-final { scan-rtl-dump-times "mem/s/u" 3 "expand" { target mips*-*-* } } } */ +/* { dg-final { cleanup-rtl-dump "expand" } } */