Reapply r131781 (revert r131809), now that some BasicAA shortcomings

it exposed are fixed.

llvm-svn: 132611
This commit is contained in:
Dan Gohman 2011-06-04 00:46:31 +00:00
parent 1b291b22d0
commit 27b82f2f91
3 changed files with 143 additions and 2 deletions

View File

@ -944,7 +944,17 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
return NoAlias;
}
return MayAlias;
// Statically, we can see that the base objects are the same, but the
// pointers have dynamic offsets which we can't resolve. And none of our
// little tricks above worked.
//
// TODO: Returning PartialAlias instead of MayAlias is a mild hack; the
// practical effect of this is protecting TBAA in the case of dynamic
// indices into arrays of unions. An alternative way to solve this would
// be to have clang emit extra metadata for unions and/or union accesses.
// A union-specific solution wouldn't handle the problem for malloc'd
// memory however.
return PartialAlias;
}
static AliasAnalysis::AliasResult

View File

@ -1,4 +1,4 @@
; RUN: opt < %s -basicaa -aa-eval -print-all-alias-modref-info -disable-output |& grep {1 may alias}
; RUN: opt < %s -basicaa -aa-eval -print-all-alias-modref-info -disable-output |& grep {1 partial alias}
; PR7959
target datalayout = "e-p:32:32:32"

View File

@ -0,0 +1,131 @@
; RUN: opt -tbaa -basicaa -gvn -S < %s | FileCheck %s
; PR9971
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
%struct.X = type { i32, float }
%union.vector_t = type { [2 x i64] }
; Don't delete the load after the loop, because it loads values stored
; inside the loop.
; CHECK: define void @vrlh(
; CHECK: for.end:
; CHECK: %arrayidx31 = getelementptr inbounds %union.vector_t* %t, i64 0, i32 0, i64 1
; CHECK: %tmp32 = load i64* %arrayidx31, align 8, !tbaa !3
define void @vrlh(%union.vector_t* %va, %union.vector_t* %vb, %union.vector_t* %vd) nounwind {
entry:
%t = alloca %union.vector_t, align 8
br label %for.body
for.body: ; preds = %entry, %for.body
%i.01 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
%sub = sub nsw i32 7, %i.01
%idxprom = sext i32 %sub to i64
%half = bitcast %union.vector_t* %vb to [8 x i16]*
%arrayidx = getelementptr inbounds [8 x i16]* %half, i64 0, i64 %idxprom
%tmp4 = load i16* %arrayidx, align 2, !tbaa !0
%conv = zext i16 %tmp4 to i32
%and = and i32 %conv, 15
%sub6 = sub nsw i32 7, %i.01
%idxprom7 = sext i32 %sub6 to i64
%half9 = bitcast %union.vector_t* %va to [8 x i16]*
%arrayidx10 = getelementptr inbounds [8 x i16]* %half9, i64 0, i64 %idxprom7
%tmp11 = load i16* %arrayidx10, align 2, !tbaa !0
%conv12 = zext i16 %tmp11 to i32
%shl = shl i32 %conv12, %and
%sub15 = sub nsw i32 7, %i.01
%idxprom16 = sext i32 %sub15 to i64
%half18 = bitcast %union.vector_t* %va to [8 x i16]*
%arrayidx19 = getelementptr inbounds [8 x i16]* %half18, i64 0, i64 %idxprom16
%tmp20 = load i16* %arrayidx19, align 2, !tbaa !0
%conv21 = zext i16 %tmp20 to i32
%sub23 = sub nsw i32 16, %and
%shr = lshr i32 %conv21, %sub23
%or = or i32 %shl, %shr
%conv24 = trunc i32 %or to i16
%sub26 = sub nsw i32 7, %i.01
%idxprom27 = sext i32 %sub26 to i64
%half28 = bitcast %union.vector_t* %t to [8 x i16]*
%arrayidx29 = getelementptr inbounds [8 x i16]* %half28, i64 0, i64 %idxprom27
store i16 %conv24, i16* %arrayidx29, align 2, !tbaa !0
%inc = add nsw i32 %i.01, 1
%cmp = icmp slt i32 %inc, 8
br i1 %cmp, label %for.body, label %for.end
for.end: ; preds = %for.body
%arrayidx31 = getelementptr inbounds %union.vector_t* %t, i64 0, i32 0, i64 1
%tmp32 = load i64* %arrayidx31, align 8, !tbaa !3
%arrayidx35 = getelementptr inbounds %union.vector_t* %vd, i64 0, i32 0, i64 1
store i64 %tmp32, i64* %arrayidx35, align 8, !tbaa !3
%arrayidx37 = getelementptr inbounds %union.vector_t* %t, i64 0, i32 0, i64 0
%tmp38 = load i64* %arrayidx37, align 8, !tbaa !3
%arrayidx41 = getelementptr inbounds %union.vector_t* %vd, i64 0, i32 0, i64 0
store i64 %tmp38, i64* %arrayidx41, align 8, !tbaa !3
ret void
}
; Do delete the load after the loop.
; CHECK: define i32 @test0(
; CHECK: ret i32 0
define i32 @test0(%struct.X* %a) nounwind {
entry:
%i = getelementptr inbounds %struct.X* %a, i64 0, i32 0
store i32 0, i32* %i, align 4, !tbaa !4
br label %for.body
for.body: ; preds = %entry, %for.body
%i2.01 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
%f = getelementptr inbounds %struct.X* %a, i64 %i2.01, i32 1
%tmp6 = load float* %f, align 4, !tbaa !5
%mul = fmul float %tmp6, 0x40019999A0000000
store float %mul, float* %f, align 4, !tbaa !5
%inc = add nsw i64 %i2.01, 1
%cmp = icmp slt i64 %inc, 10000
br i1 %cmp, label %for.body, label %for.end
for.end: ; preds = %for.body
%i9 = getelementptr inbounds %struct.X* %a, i64 0, i32 0
%tmp10 = load i32* %i9, align 4, !tbaa !4
ret i32 %tmp10
}
; Do delete the load after the loop.
; CHECK: define float @test1(
; CHECK: ret float 0x3FD3333340000000
define float @test1(%struct.X* %a) nounwind {
entry:
%f = getelementptr inbounds %struct.X* %a, i64 0, i32 1
store float 0x3FD3333340000000, float* %f, align 4, !tbaa !5
br label %for.body
for.body: ; preds = %entry, %for.body
%i.01 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
%i5 = getelementptr inbounds %struct.X* %a, i64 %i.01, i32 0
%tmp6 = load i32* %i5, align 4, !tbaa !4
%mul = mul nsw i32 %tmp6, 3
store i32 %mul, i32* %i5, align 4, !tbaa !4
%inc = add nsw i64 %i.01, 1
%cmp = icmp slt i64 %inc, 10000
br i1 %cmp, label %for.body, label %for.end
for.end: ; preds = %for.body
%f9 = getelementptr inbounds %struct.X* %a, i64 0, i32 1
%tmp10 = load float* %f9, align 4, !tbaa !5
ret float %tmp10
}
!0 = metadata !{metadata !"short", metadata !1}
!1 = metadata !{metadata !"omnipotent char", metadata !2}
!2 = metadata !{metadata !"Simple C/C++ TBAA", null}
!3 = metadata !{metadata !"long long", metadata !1}
!4 = metadata !{metadata !"int", metadata !1}
!5 = metadata !{metadata !"float", metadata !1}