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middle-end/106331 - fix mem attributes for string op arguments 

get_memory_rtx tries hard to come up with a MEM_EXPR to record
in the memory attributes but in the last fallback fails to properly
account for an unknown offset and thus, as visible in this testcase,
incorrect alignment computed from set_mem_attributes.  The following
rectifies both parts.

	PR middle-end/106331
	* builtins.cc (get_memory_rtx): Compute alignment from
	the original address and set MEM_OFFSET to unknown when
	we create a MEM_EXPR from the base object of the address.

	* gfortran.dg/pr106331.f90: New testcase.

(cherry picked from commit e4ff11a8f2)
This commit is contained in:
Richard Biener 2022-07-19 09:57:22 +02:00
parent ec9287ba97
commit 1a7200da71
2 changed files with 16 additions and 4 deletions
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13
gcc/builtins.cc
View File

@ -1360,7 +1360,7 @@ expand_builtin_prefetch (tree exp)
rtx
get_memory_rtx (tree exp, tree len)
{
tree orig_exp = exp;
tree orig_exp = exp, base;
rtx addr, mem;
/* When EXP is not resolved SAVE_EXPR, MEM_ATTRS can be still derived
@ -1391,10 +1391,11 @@ get_memory_rtx (tree exp, tree len)
if (is_gimple_mem_ref_addr (TREE_OPERAND (exp, 0)))
set_mem_attributes (mem, exp, 0);
else if (TREE_CODE (TREE_OPERAND (exp, 0)) == ADDR_EXPR
&& (exp = get_base_address (TREE_OPERAND (TREE_OPERAND (exp, 0),
0))))
&& (base = get_base_address (TREE_OPERAND (TREE_OPERAND (exp, 0),
0))))
{
exp = build_fold_addr_expr (exp);
unsigned int align = get_pointer_alignment (TREE_OPERAND (exp, 0));
exp = build_fold_addr_expr (base);
exp = fold_build2 (MEM_REF,
build_array_type (char_type_node,
build_range_type (sizetype,
@ -1402,6 +1403,10 @@ get_memory_rtx (tree exp, tree len)
NULL)),
exp, build_int_cst (ptr_type_node, 0));
set_mem_attributes (mem, exp, 0);
/* Since we stripped parts make sure the offset is unknown and the
alignment is computed from the original address. */
clear_mem_offset (mem);
set_mem_align (mem, align);
}
set_mem_alias_set (mem, 0);
return mem;

7
gcc/testsuite/gfortran.dg/pr106331.f90 Normal file
View File

@ -0,0 +1,7 @@
! { dg-do run }
! { dg-options "-Og" }
PROGRAM main
CHARACTER(LEN=24) :: a(2)
a = ''
END PROGRAM