Make the MemCpyOptimizer a bit more aggressive. I can't think of a scenerio

where this would be bad as the backend shouldn't have a problem inlining small
memcpys.
rdar://10510150

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145865 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index 9e4f51f4549318951eca73fd729efb10795a1427..6c6db60cc3eb9c20c2f094992c808e1c9b0accfd 100644 (file)
--- a/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -148,7 +148,7 @@ struct MemsetRange {
 
 bool MemsetRange::isProfitableToUseMemset(const TargetData &TD) const {
   // If we found more than 8 stores to merge or 64 bytes, use memset.
-  if (TheStores.size() >= 8 || End-Start >= 64) return true;
+  if (TheStores.size() >= 4 || End-Start >= 16) return true;
 
   // If there is nothing to merge, don't do anything.
   if (TheStores.size() < 2) return false;

diff --git a/test/Transforms/MemCpyOpt/form-memset.ll b/test/Transforms/MemCpyOpt/form-memset.ll
index 1ac97e9e6b91fbea0d365ab8ba8b7aad6d87e4e3..e5ace33270296cc133388b5cbbcf247a6b31c45a 100644 (file)
--- a/test/Transforms/MemCpyOpt/form-memset.ll
+++ b/test/Transforms/MemCpyOpt/form-memset.ll
@@ -57,8 +57,8 @@ entry:
 
 declare i32 @bar(...)
 
+%struct.MV = type { i16, i16 }
 
-       %struct.MV = type { i16, i16 }
 
 define void @test2() nounwind  {
 entry:
@@ -220,3 +220,19 @@ entry:
 ; CHECK: call void @llvm.memset.p0i8.i64(i8* %2, i8 0, i64 24, i32 1, i1 false)
 }
 
+; More aggressive heuristic
+; rdar://9892684
+define void @test7(i32* nocapture %c) nounwind optsize {
+  store i32 -1, i32* %c, align 4
+  %1 = getelementptr inbounds i32* %c, i32 1
+  store i32 -1, i32* %1, align 4
+  %2 = getelementptr inbounds i32* %c, i32 2
+  store i32 -1, i32* %2, align 4
+  %3 = getelementptr inbounds i32* %c, i32 3
+  store i32 -1, i32* %3, align 4
+  %4 = getelementptr inbounds i32* %c, i32 4
+  store i32 -1, i32* %4, align 4
+; CHECK: @test7
+; CHECK: call void @llvm.memset.p0i8.i64(i8* %5, i8 -1, i64 20, i32 4, i1 false)
+  ret void
+}