When scalar replacement returns a vector type, only accept it if the vector

type's bitwidth matches the (allocated) size of the alloca. This severely
pessimizes vector scalar replacement when the only vector type being used is
something like <3 x float> on x86 or ARM whose allocated size matches a
<4 x float>.

I hope to fix some of the flawed assumptions about allocated size throughout
scalar replacement and reenable this in most cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133338 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/ScalarReplAggregates.cpp b/lib/Transforms/Scalar/ScalarReplAggregates.cpp
index 38942dcb55cb9c4f3748dada786759d86c731569..46ac9482006142926909cec1b9dfcb70f374caed 100644 (file)
--- a/lib/Transforms/Scalar/ScalarReplAggregates.cpp
+++ b/lib/Transforms/Scalar/ScalarReplAggregates.cpp
@@ -293,6 +293,11 @@ AllocaInst *ConvertToScalarInfo::TryConvert(AllocaInst *AI) {
   if (ScalarKind == Unknown)
     ScalarKind = Integer;
 
+  // FIXME: It should be possible to promote the vector type up to the alloca's
+  // size.
+  if (ScalarKind == Vector && VectorTy->getBitWidth() != AllocaSize * 8)
+    ScalarKind = Integer;
+
   // If we were able to find a vector type that can handle this with
   // insert/extract elements, and if there was at least one use that had
   // a vector type, promote this to a vector.  We don't want to promote

diff --git a/test/Transforms/ScalarRepl/2011-06-08-VectorExtractValue.ll b/test/Transforms/ScalarRepl/2011-06-08-VectorExtractValue.ll
index 32e67fbce78b3446fc061551ce762ab62256dea1..98fa1c684ce19751a5ede95f220077bb090d715c 100644 (file)
--- a/test/Transforms/ScalarRepl/2011-06-08-VectorExtractValue.ll
+++ b/test/Transforms/ScalarRepl/2011-06-08-VectorExtractValue.ll
@@ -10,7 +10,8 @@ target triple = "x86_64-apple-macosx10.7.0"
 
 ; CHECK: main
 ; CHECK-NOT: alloca
-; CHECK: extractelement <2 x float> zeroinitializer
+; CHECK: %[[A:[a-z0-9]*]] = and i128
+; CHECK: %[[B:[a-z0-9]*]] = trunc i128 %[[A]] to i32
 
 define void @main() uwtable ssp {
 entry:
@@ -27,7 +28,8 @@ entry:
 
 ; CHECK: test1
 ; CHECK-NOT: alloca
-; CHECK: extractelement <2 x float> zeroinitializer
+; CHECK: %[[A:[a-z0-9]*]] = and i128
+; CHECK: %[[B:[a-z0-9]*]] = trunc i128 %[[A]] to i32
 
 define void @test1() uwtable ssp {
 entry:

diff --git a/test/Transforms/ScalarRepl/2011-06-17-VectorPartialMemset.ll b/test/Transforms/ScalarRepl/2011-06-17-VectorPartialMemset.ll
index 29d195eba361c0cb7915360d21e459976a92a5ea..f8530d68a8fb9ffab6a0ddb9db833dd51ada03cb 100644 (file)
--- a/test/Transforms/ScalarRepl/2011-06-17-VectorPartialMemset.ll
+++ b/test/Transforms/ScalarRepl/2011-06-17-VectorPartialMemset.ll
@@ -19,4 +19,19 @@ entry:
   ret float %val
 }
 
+; CHECK: g
+; CHECK-NOT: alloca
+; CHECK: and i128
+
+define void @g() nounwind ssp {
+entry:
+  %a = alloca { <4 x float> }, align 16
+  %p = bitcast { <4 x float> }* %a to i8*
+  call void @llvm.memset.p0i8.i32(i8* %p, i8 0, i32 16, i32 16, i1 false)
+  %q = bitcast { <4 x float> }* %a to [2 x <2 x float>]*
+  %arrayidx = getelementptr inbounds [2 x <2 x float>]* %q, i32 0, i32 0
+  store <2 x float> undef, <2 x float>* %arrayidx, align 8
+  ret void
+}
+
 declare void @llvm.memset.p0i8.i32(i8* nocapture, i8, i32, i32, i1) nounwind