re PR lto/61886 (LTO breaks fread with _FORTIFY_SOURCE=2)
PR ipa/61886 PR middle-end/25140 * tree-ssa-alias.c (ptr_deref_may_alias_decl_p): Use compare_base_decls (nonoverlapping_component_refs_of_decl_p): Update sanity check. (decl_refs_may_alias_p): Use compare_base_decls. * alias.c: Include cgraph.h (rtx_equal_for_memref_p): Use rtx_equal_for_memref_p. (compare_base_decls): New function. (base_alias_check): Likewise. (memrefs_conflict_p): Likewise. (nonoverlapping_memrefs_p): Likewise. * alias.h (compare_base_decls): Declare. * gcc.c-torture/execute/alias-2.c: New testcase. From-SVN: r231478
This commit is contained in:
Jan Hubicka
Jan Hubicka
parent
da20571a7c
commit
54363f8a92
6 changed files with 126 additions and 7 deletions
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@ -1,3 +1,18 @@
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2015-12-08 Jan Hubicka <hubicka@ucw.cz>
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PR ipa/61886
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PR middle-end/25140
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* tree-ssa-alias.c (ptr_deref_may_alias_decl_p): Use compare_base_decls
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(nonoverlapping_component_refs_of_decl_p): Update sanity check.
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(decl_refs_may_alias_p): Use compare_base_decls.
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* alias.c: Include cgraph.h
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(rtx_equal_for_memref_p): Use rtx_equal_for_memref_p.
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(compare_base_decls): New function.
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(base_alias_check): Likewise.
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(memrefs_conflict_p): Likewise.
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(nonoverlapping_memrefs_p): Likewise.
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* alias.h (compare_base_decls): Declare.
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2015-12-08 Jan Hubicka <hubicka@ucw.cz>
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PR ipa/61886
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89
gcc/alias.c
89
gcc/alias.c
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@ -37,6 +37,7 @@ along with GCC; see the file COPYING3. If not see
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#include "langhooks.h"
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#include "cfganal.h"
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#include "rtl-iter.h"
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#include "cgraph.h"
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/* The aliasing API provided here solves related but different problems:
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@ -990,6 +991,14 @@ get_alias_set (tree t)
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|| TREE_CODE (p) == VECTOR_TYPE;
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p = TREE_TYPE (p))
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{
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/* Ada supports recusive pointers. Instead of doing recrusion check
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just give up once the preallocated space of 8 elements is up.
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In this case just punt to void * alias set. */
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if (reference.length () == 8)
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{
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p = ptr_type_node;
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break;
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}
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if (TREE_CODE (p) == REFERENCE_TYPE)
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/* In LTO we want languages that use references to be compatible
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with languages that use pointers. */
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@ -1747,7 +1756,15 @@ rtx_equal_for_memref_p (const_rtx x, const_rtx y)
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return LABEL_REF_LABEL (x) == LABEL_REF_LABEL (y);
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case SYMBOL_REF:
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return XSTR (x, 0) == XSTR (y, 0);
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{
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tree x_decl = SYMBOL_REF_DECL (x);
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tree y_decl = SYMBOL_REF_DECL (y);
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if (!x_decl || !y_decl)
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return XSTR (x, 0) == XSTR (y, 0);
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else
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return compare_base_decls (x_decl, y_decl) == 1;
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}
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case ENTRY_VALUE:
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/* This is magic, don't go through canonicalization et al. */
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@ -2010,6 +2027,31 @@ may_be_sp_based_p (rtx x)
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return !base || base == static_reg_base_value[STACK_POINTER_REGNUM];
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}
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/* BASE1 and BASE2 are decls. Return 1 if they refer to same object, 0
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if they refer to different objects and -1 if we can not decide. */
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int
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compare_base_decls (tree base1, tree base2)
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{
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int ret;
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gcc_checking_assert (DECL_P (base1) && DECL_P (base2));
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if (base1 == base2)
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return 1;
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bool in_symtab1 = decl_in_symtab_p (base1);
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bool in_symtab2 = decl_in_symtab_p (base2);
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/* Declarations of non-automatic variables may have aliases. All other
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decls are unique. */
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if (in_symtab1 != in_symtab2 || !in_symtab1)
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return 0;
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ret = symtab_node::get_create (base1)->equal_address_to
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(symtab_node::get_create (base2), true);
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if (ret == 2)
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return -1;
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return ret;
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}
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/* Return 0 if the addresses X and Y are known to point to different
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objects, 1 if they might be pointers to the same object. */
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@ -2047,6 +2089,17 @@ base_alias_check (rtx x, rtx x_base, rtx y, rtx y_base,
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if (rtx_equal_p (x_base, y_base))
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return 1;
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if (GET_CODE (x_base) == SYMBOL_REF && GET_CODE (y_base) == SYMBOL_REF)
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{
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tree x_decl = SYMBOL_REF_DECL (x_base);
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tree y_decl = SYMBOL_REF_DECL (y_base);
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/* We can assume that no stores are made to labels. */
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if (!x_decl || !y_decl)
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return 0;
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return compare_base_decls (x_decl, y_decl) != 0;
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}
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/* The base addresses are different expressions. If they are not accessed
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via AND, there is no conflict. We can bring knowledge of object
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alignment into play here. For example, on alpha, "char a, b;" can
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@ -2268,7 +2321,33 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
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else
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y = addr_side_effect_eval (y, abs (ysize), 0);
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if (rtx_equal_for_memref_p (x, y))
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if (GET_CODE (x) == SYMBOL_REF && GET_CODE (y) == SYMBOL_REF)
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{
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tree x_decl = SYMBOL_REF_DECL (x);
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tree y_decl = SYMBOL_REF_DECL (y);
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int cmp;
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if (!x_decl || !y_decl)
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{
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/* Label and normal symbol are never the same. */
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if (x_decl != y_decl)
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return 0;
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return offset_overlap_p (c, xsize, ysize);
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}
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else
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cmp = compare_base_decls (x_decl, y_decl);
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/* If both decls are the same, decide by offsets. */
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if (cmp == 1)
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return offset_overlap_p (c, xsize, ysize);
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/* If decls are different or we know by offsets that there is no overlap,
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we win. */
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if (!cmp || !offset_overlap_p (c, xsize, ysize))
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return 0;
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/* Decls may or may not be different and offsets overlap....*/
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return -1;
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}
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else if (rtx_equal_for_memref_p (x, y))
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{
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return offset_overlap_p (c, xsize, ysize);
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}
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@ -2636,7 +2715,7 @@ nonoverlapping_memrefs_p (const_rtx x, const_rtx y, bool loop_invariant)
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are constants or if one is a constant and the other a pointer into the
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stack frame. Otherwise a different base means we can't tell if they
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overlap or not. */
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if (! rtx_equal_p (basex, basey))
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if (compare_base_decls (exprx, expry) == 0)
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return ((CONSTANT_P (basex) && CONSTANT_P (basey))
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|| (CONSTANT_P (basex) && REG_P (basey)
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&& REGNO_PTR_FRAME_P (REGNO (basey)))
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@ -2647,6 +2726,10 @@ nonoverlapping_memrefs_p (const_rtx x, const_rtx y, bool loop_invariant)
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if (loop_invariant)
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return 0;
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/* Offset based disambiguation is OK even if we do not know that the
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declarations are necessarily different
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(i.e. compare_base_decls (exprx, expry) == -1) */
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sizex = (!MEM_P (rtlx) ? (int) GET_MODE_SIZE (GET_MODE (rtlx))
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: MEM_SIZE_KNOWN_P (rtlx) ? MEM_SIZE (rtlx)
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: -1);
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@ -36,6 +36,7 @@ extern int nonoverlapping_memrefs_p (const_rtx, const_rtx, bool);
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extern void dump_alias_stats_in_alias_c (FILE *s);
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tree reference_alias_ptr_type (tree);
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bool alias_ptr_types_compatible_p (tree, tree);
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int compare_base_decls (tree, tree);
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/* This alias set can be used to force a memory to conflict with all
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other memories, creating a barrier across which no memory reference
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@ -1,3 +1,9 @@
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2015-12-08 Jan Hubicka <hubicka@ucw.cz>
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PR ipa/61886
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PR middle-end/25140
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* gcc.c-torture/execute/alias-2.c: New testcase.
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2015-12-09 Tobias Burnus <burnus@net-b.de>
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Alessandro Fanfarillo <fanfarillo.gcc@gmail.com>
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12
gcc/testsuite/gcc.c-torture/execute/alias-2.c
Normal file
12
gcc/testsuite/gcc.c-torture/execute/alias-2.c
Normal file
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@ -0,0 +1,12 @@
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/* { dg-require-alias "" } */
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int a[10]={};
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extern int b[10] __attribute__ ((alias("a")));
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int off;
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main()
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{
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b[off]=1;
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a[off]=2;
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if (b[off]!=2)
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__builtin_abort ();
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return 0;
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}
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@ -194,7 +194,7 @@ ptr_deref_may_alias_decl_p (tree ptr, tree decl)
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ptr = TREE_OPERAND (base, 0);
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else if (base
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&& DECL_P (base))
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return base == decl;
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return compare_base_decls (base, decl) != 0;
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else if (base
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&& CONSTANT_CLASS_P (base))
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return false;
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@ -805,8 +805,10 @@ nonoverlapping_component_refs_of_decl_p (tree ref1, tree ref2)
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ref2 = TREE_OPERAND (TREE_OPERAND (ref2, 0), 0);
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}
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/* We must have the same base DECL. */
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gcc_assert (ref1 == ref2);
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/* Bases must be either same or uncomparable. */
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gcc_checking_assert (ref1 == ref2
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|| (DECL_P (ref1) && DECL_P (ref2)
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&& compare_base_decls (ref1, ref2) != 0));
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/* Pop the stacks in parallel and examine the COMPONENT_REFs of the same
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rank. This is sufficient because we start from the same DECL and you
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@ -989,7 +991,7 @@ decl_refs_may_alias_p (tree ref1, tree base1,
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gcc_checking_assert (DECL_P (base1) && DECL_P (base2));
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/* If both references are based on different variables, they cannot alias. */
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if (base1 != base2)
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if (compare_base_decls (base1, base2) == 0)
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return false;
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/* If both references are based on the same variable, they cannot alias if
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