From 5ffca72c5db83f53562a968a30d3955126f044f2 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Wed, 20 Dec 2017 12:52:50 +0000 Subject: [PATCH] poly_int: indirect_refs_may_alias_p This patch makes indirect_refs_may_alias_p use ranges_may_overlap_p rather than ranges_overlap_p. Unlike the former, the latter can handle negative offsets, so the fix for PR44852 should no longer be necessary. It can also handle offset_int, so avoids unchecked truncations to HOST_WIDE_INT. 2017-12-20 Richard Sandiford Alan Hayward David Sherwood gcc/ * tree-ssa-alias.c (indirect_ref_may_alias_decl_p) (indirect_refs_may_alias_p): Use ranges_may_overlap_p instead of ranges_overlap_p. Co-Authored-By: Alan Hayward Co-Authored-By: David Sherwood From-SVN: r255871 --- gcc/ChangeLog | 8 ++++++++ gcc/tree-ssa-alias.c | 49 +++++++++----------------------------------- 2 files changed, 18 insertions(+), 39 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index a08c80bed1b..d69e2441aed 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2017-12-20 Richard Sandiford + Alan Hayward + David Sherwood + + * tree-ssa-alias.c (indirect_ref_may_alias_decl_p) + (indirect_refs_may_alias_p): Use ranges_may_overlap_p + instead of ranges_overlap_p. + 2017-12-20 Richard Sandiford Alan Hayward David Sherwood diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c index 4d46162791f..8717a1f356c 100644 --- a/gcc/tree-ssa-alias.c +++ b/gcc/tree-ssa-alias.c @@ -1135,23 +1135,13 @@ indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1, { tree ptr1; tree ptrtype1, dbase2; - HOST_WIDE_INT offset1p = offset1, offset2p = offset2; - HOST_WIDE_INT doffset1, doffset2; gcc_checking_assert ((TREE_CODE (base1) == MEM_REF || TREE_CODE (base1) == TARGET_MEM_REF) && DECL_P (base2)); ptr1 = TREE_OPERAND (base1, 0); - - /* The offset embedded in MEM_REFs can be negative. Bias them - so that the resulting offset adjustment is positive. */ - offset_int moff = mem_ref_offset (base1); - moff <<= LOG2_BITS_PER_UNIT; - if (wi::neg_p (moff)) - offset2p += (-moff).to_short_addr (); - else - offset1p += moff.to_short_addr (); + offset_int moff = mem_ref_offset (base1) << LOG2_BITS_PER_UNIT; /* If only one reference is based on a variable, they cannot alias if the pointer access is beyond the extent of the variable access. @@ -1160,7 +1150,7 @@ indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1, ??? IVOPTs creates bases that do not honor this restriction, so do not apply this optimization for TARGET_MEM_REFs. */ if (TREE_CODE (base1) != TARGET_MEM_REF - && !ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2)) + && !ranges_maybe_overlap_p (offset1 + moff, -1, offset2, max_size2)) return false; /* They also cannot alias if the pointer may not point to the decl. */ if (!ptr_deref_may_alias_decl_p (ptr1, base2)) @@ -1213,18 +1203,11 @@ indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1, dbase2 = ref2; while (handled_component_p (dbase2)) dbase2 = TREE_OPERAND (dbase2, 0); - doffset1 = offset1; - doffset2 = offset2; + HOST_WIDE_INT doffset1 = offset1; + offset_int doffset2 = offset2; if (TREE_CODE (dbase2) == MEM_REF || TREE_CODE (dbase2) == TARGET_MEM_REF) - { - offset_int moff = mem_ref_offset (dbase2); - moff <<= LOG2_BITS_PER_UNIT; - if (wi::neg_p (moff)) - doffset1 -= (-moff).to_short_addr (); - else - doffset2 -= moff.to_short_addr (); - } + doffset2 -= mem_ref_offset (dbase2) << LOG2_BITS_PER_UNIT; /* If either reference is view-converted, give up now. */ if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1 @@ -1241,7 +1224,7 @@ indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1, if ((TREE_CODE (base1) != TARGET_MEM_REF || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1))) && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (dbase2)) == 1) - return ranges_overlap_p (doffset1, max_size1, doffset2, max_size2); + return ranges_maybe_overlap_p (doffset1, max_size1, doffset2, max_size2); if (ref1 && ref2 && nonoverlapping_component_refs_p (ref1, ref2)) @@ -1313,22 +1296,10 @@ indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1, && operand_equal_p (TMR_INDEX2 (base1), TMR_INDEX2 (base2), 0)))))) { - offset_int moff; - /* The offset embedded in MEM_REFs can be negative. Bias them - so that the resulting offset adjustment is positive. */ - moff = mem_ref_offset (base1); - moff <<= LOG2_BITS_PER_UNIT; - if (wi::neg_p (moff)) - offset2 += (-moff).to_short_addr (); - else - offset1 += moff.to_shwi (); - moff = mem_ref_offset (base2); - moff <<= LOG2_BITS_PER_UNIT; - if (wi::neg_p (moff)) - offset1 += (-moff).to_short_addr (); - else - offset2 += moff.to_short_addr (); - return ranges_overlap_p (offset1, max_size1, offset2, max_size2); + offset_int moff1 = mem_ref_offset (base1) << LOG2_BITS_PER_UNIT; + offset_int moff2 = mem_ref_offset (base2) << LOG2_BITS_PER_UNIT; + return ranges_maybe_overlap_p (offset1 + moff1, max_size1, + offset2 + moff2, max_size2); } if (!ptr_derefs_may_alias_p (ptr1, ptr2)) return false; -- 2.30.2