[MemCpyOpt] Update to new API for memory intrinsic alignment

Summary:
This change is part of step five in the series of changes to remove alignment argument from
memcpy/memmove/memset in favour of alignment attributes. In particular, this changes the
MemCpyOpt pass to cease using:
1) The old getAlignment() API of MemoryIntrinsic in favour of getting source & dest specific
alignments through the new API.
2) The old IRBuilder CreateMemCpy/CreateMemMove single-alignment APIs in favour of the new
API that allows setting source and destination alignments independently.

We also add a few tests to fill gaps in the testing of this pass.

Steps:
Step 1) Remove alignment parameter and create alignment parameter attributes for
memcpy/memmove/memset. ( rL322965, rC322964, rL322963 )
Step 2) Expand the IRBuilder API to allow creation of memcpy/memmove with differing
source and dest alignments. ( rL323597 )
Step 3) Update Clang to use the new IRBuilder API. ( rC323617 )
Step 4) Update Polly to use the new IRBuilder API. ( rL323618 )
Step 5) Update LLVM passes that create memcpy/memmove calls to use the new IRBuilder API,
and those that use use MemIntrinsicInst::[get|set]Alignment() to use [get|set]DestAlignment()
and [get|set]SourceAlignment() instead. ( rL323886, rL323891, rL324148, rL324273, rL324278,
rL324384, rL324395, rL324402, rL324626, rL324642, rL324653, rL324654, rL324773, rL324774,
rL324781, rL324784, rL324955, rL324960, rL325816, rL327398, rL327421 )
Step 6) Remove the single-alignment IRBuilder API for memcpy/memmove, and the
MemIntrinsicInst::[get|set]Alignment() methods.

Reference
   http://lists.llvm.org/pipermail/llvm-dev/2015-August/089384.html
   http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html

llvm-svn: 328097

2 files changed, 42 insertions, 0 deletions

diff --git a/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll b/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll
index f6b175e4171..9dbba093fe2 100644
--- a/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll
+++ b/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll
@@ -3,6 +3,34 @@
 
 %T = type { i8, i32 }
 
+; Ensure load-store forwarding of an aggregate is interpreted as
+; a memmove when the source and dest may alias
+define void @test_memmove(%T* align 8 %a, %T* align 16 %b) {
+; CHECK-LABEL: @test_memmove(
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast %T* [[B:%.*]] to i8*
+; CHECK-NEXT:    [[TMP2:%.*]] = bitcast %T* [[A:%.*]] to i8*
+; CHECK-NEXT:    call void @llvm.memmove.p0i8.p0i8.i64(i8* align 16 [[TMP1]], i8* align 8 [[TMP2]], i64 8, i1 false)
+; CHECK-NEXT:    ret void
+;
+  %val = load %T, %T* %a, align 8
+  store %T %val, %T* %b, align 16
+  ret void
+}
+
+; Ensure load-store forwarding of an aggregate is interpreted as
+; a memcpy when the source and dest do not alias
+define void @test_memcpy(%T* noalias align 8 %a, %T* noalias align 16 %b) {
+; CHECK-LABEL: @test_memcpy(
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast %T* [[B:%.*]] to i8*
+; CHECK-NEXT:    [[TMP2:%.*]] = bitcast %T* [[A:%.*]] to i8*
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 16 [[TMP1]], i8* align 8 [[TMP2]], i64 8, i1 false)
+; CHECK-NEXT:    ret void
+;
+  %val = load %T, %T* %a, align 8
+  store %T %val, %T* %b, align 16
+  ret void
+}
+
 ; memcpy(%d, %a) should not be generated since store2 may-aliases load %a.
 define void @f(%T* %a, %T* %b, %T* %c, %T* %d) {
 ; CHECK-LABEL: @f(
diff --git a/llvm/test/Transforms/MemCpyOpt/memcpy.ll b/llvm/test/Transforms/MemCpyOpt/memcpy.ll
index 7e1e4d54a24..4c5f6cbeb1a 100644
--- a/llvm/test/Transforms/MemCpyOpt/memcpy.ll
+++ b/llvm/test/Transforms/MemCpyOpt/memcpy.ll
@@ -46,6 +46,20 @@ define void @test2(i8* %P, i8* %Q) nounwind  {
 ; CHECK-NEXT: ret void
 }
 
+; The intermediate alloca and one of the memcpy's should be eliminated, the
+; other should be related with a memcpy.
+define void @test2_memcpy(i8* noalias %P, i8* noalias %Q) nounwind  {
+  %memtmp = alloca %0, align 16
+  %R = bitcast %0* %memtmp to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 16 %R, i8* align 16 %P, i32 32, i1 false)
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 16 %Q, i8* align 16 %R, i32 32, i1 false)
+  ret void
+
+; CHECK-LABEL: @test2_memcpy(
+; CHECK-NEXT: call void @llvm.memcpy{{.*}}(i8* align 16 %Q, i8* align 16 %P
+; CHECK-NEXT: ret void
+}
+