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

it exposed are fixed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132611 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index 24297d4a0f3cf39c9465c04552c3df9c40ca9b6f..3d10a5fd4d76fc6a0dcd776346049729d0e5b937 100644 (file)
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -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

diff --git a/test/Analysis/BasicAA/2010-09-15-GEP-SignedArithmetic.ll b/test/Analysis/BasicAA/2010-09-15-GEP-SignedArithmetic.ll
index 2b0cd78fece30bf9eda81d213feac3baef498e77..7b5584e0bd8b1b9f09501e5df09e8495d1467338 100644 (file)
--- a/test/Analysis/BasicAA/2010-09-15-GEP-SignedArithmetic.ll
+++ b/test/Analysis/BasicAA/2010-09-15-GEP-SignedArithmetic.ll
@@ -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"

diff --git a/test/Analysis/TypeBasedAliasAnalysis/dynamic-indices.ll b/test/Analysis/TypeBasedAliasAnalysis/dynamic-indices.ll
new file mode 100644 (file)
index 0000000..52e394b
--- /dev/null
+++ b/test/Analysis/TypeBasedAliasAnalysis/dynamic-indices.ll
@@ -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}