[MemCpyOpt] Look through pointer casts when checking capture

The user scanning loop above looks through pointer casts, so we
also need to strip pointer casts in the capture check. Previously
the source was incorrectly considered not captured if a bitcast
was passed to the call.

diff --git a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index d6723ff..1384740 100644 (file)
--- a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -949,7 +949,8 @@ bool MemCpyOptPass::performCallSlotOptzn(Instruction *cpyLoad,
   // Check whether src is captured by the called function, in which case there
   // may be further indirect uses of src.
   bool SrcIsCaptured = any_of(C->args(), [&](Use &U) {
-    return U == cpySrc && !C->doesNotCapture(C->getArgOperandNo(&U));
+    return U->stripPointerCasts() == cpySrc &&
+           !C->doesNotCapture(C->getArgOperandNo(&U));
   });
 
   // If src is captured, then check whether there are any potential uses of

diff --git a/llvm/test/Transforms/MemCpyOpt/callslot.ll b/llvm/test/Transforms/MemCpyOpt/callslot.ll
index c118646..5cb5702 100644 (file)
--- a/llvm/test/Transforms/MemCpyOpt/callslot.ll
+++ b/llvm/test/Transforms/MemCpyOpt/callslot.ll
@@ -172,7 +172,7 @@ define void @capture_before_call_argmemonly() {
 ; CHECK-NEXT:    [[SRC_I8:%.*]] = bitcast [16 x i8]* [[SRC]] to i8*
 ; CHECK-NEXT:    call void @accept_ptr(i8* [[DEST_I8]])
 ; CHECK-NEXT:    [[DEST1:%.*]] = bitcast [16 x i8]* [[DEST]] to i8*
-; CHECK-NEXT:    call void @accept_ptr(i8* [[DEST1]]) #[[ATTR4:[0-9]+]]
+; CHECK-NEXT:    call void @accept_ptr(i8* nocapture [[DEST1]]) #[[ATTR4:[0-9]+]]
 ; CHECK-NEXT:    ret void
 ;
   %dest = alloca [16 x i8]
@@ -180,7 +180,7 @@ define void @capture_before_call_argmemonly() {
   %dest.i8 = bitcast [16 x i8]* %dest to i8*
   %src.i8 = bitcast [16 x i8]* %src to i8*
   call void @accept_ptr(i8* %dest.i8) ; capture
-  call void @accept_ptr(i8* %src.i8) argmemonly
+  call void @accept_ptr(i8* nocapture %src.i8) argmemonly
   call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dest.i8, i8* %src.i8, i64 16, i1 false)
   ret void
 }
@@ -193,7 +193,7 @@ define void @capture_before_call_argmemonly_nounwind() {
 ; CHECK-NEXT:    [[SRC_I8:%.*]] = bitcast [16 x i8]* [[SRC]] to i8*
 ; CHECK-NEXT:    call void @accept_ptr(i8* [[DEST_I8]])
 ; CHECK-NEXT:    [[DEST1:%.*]] = bitcast [16 x i8]* [[DEST]] to i8*
-; CHECK-NEXT:    call void @accept_ptr(i8* [[DEST1]]) #[[ATTR5:[0-9]+]]
+; CHECK-NEXT:    call void @accept_ptr(i8* nocapture [[DEST1]]) #[[ATTR5:[0-9]+]]
 ; CHECK-NEXT:    ret void
 ;
   %dest = alloca [16 x i8]
@@ -202,7 +202,7 @@ define void @capture_before_call_argmemonly_nounwind() {
   %src.i8 = bitcast [16 x i8]* %src to i8*
   call void @accept_ptr(i8* %dest.i8) ; capture
   ; NB: argmemonly currently implies willreturn.
-  call void @accept_ptr(i8* %src.i8) argmemonly nounwind
+  call void @accept_ptr(i8* nocapture %src.i8) argmemonly nounwind
   call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dest.i8, i8* %src.i8, i64 16, i1 false)
   ret void
 }
@@ -215,7 +215,7 @@ define void @capture_before_call_argmemonly_nounwind_willreturn() {
 ; CHECK-NEXT:    [[SRC_I8:%.*]] = bitcast [16 x i8]* [[SRC]] to i8*
 ; CHECK-NEXT:    call void @accept_ptr(i8* [[DEST_I8]])
 ; CHECK-NEXT:    [[DEST1:%.*]] = bitcast [16 x i8]* [[DEST]] to i8*
-; CHECK-NEXT:    call void @accept_ptr(i8* [[DEST1]]) #[[ATTR6:[0-9]+]]
+; CHECK-NEXT:    call void @accept_ptr(i8* nocapture [[DEST1]]) #[[ATTR6:[0-9]+]]
 ; CHECK-NEXT:    ret void
 ;
   %dest = alloca [16 x i8]
@@ -223,7 +223,7 @@ define void @capture_before_call_argmemonly_nounwind_willreturn() {
   %dest.i8 = bitcast [16 x i8]* %dest to i8*
   %src.i8 = bitcast [16 x i8]* %src to i8*
   call void @accept_ptr(i8* %dest.i8) ; capture
-  call void @accept_ptr(i8* %src.i8) argmemonly nounwind willreturn
+  call void @accept_ptr(i8* nocapture %src.i8) argmemonly nounwind willreturn
   call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dest.i8, i8* %src.i8, i64 16, i1 false)
   ret void
 }

diff --git a/llvm/test/Transforms/MemCpyOpt/capturing-func.ll b/llvm/test/Transforms/MemCpyOpt/capturing-func.ll
index 4099e3c..84c1446 100644 (file)
--- a/llvm/test/Transforms/MemCpyOpt/capturing-func.ll
+++ b/llvm/test/Transforms/MemCpyOpt/capturing-func.ll
@@ -28,15 +28,14 @@ define void @test() {
 }
 
 ; Same as previous test, but with a bitcasted argument.
-; TODO: Call slot optimization should not be applied here.
 define void @test_bitcast() {
 ; CHECK-LABEL: define {{[^@]+}}@test_bitcast() {
 ; CHECK-NEXT:    [[PTR1:%.*]] = alloca [2 x i8], align 1
 ; CHECK-NEXT:    [[PTR2:%.*]] = alloca [2 x i8], align 1
 ; CHECK-NEXT:    [[PTR1_CAST:%.*]] = bitcast [2 x i8]* [[PTR1]] to i8*
 ; CHECK-NEXT:    [[PTR2_CAST:%.*]] = bitcast [2 x i8]* [[PTR2]] to i8*
-; CHECK-NEXT:    [[PTR11:%.*]] = bitcast [2 x i8]* [[PTR1]] to i8*
-; CHECK-NEXT:    call void @foo(i8* [[PTR11]])
+; CHECK-NEXT:    call void @foo(i8* [[PTR2_CAST]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* [[PTR1_CAST]], i8* [[PTR2_CAST]], i32 2, i1 false)
 ; CHECK-NEXT:    call void @foo(i8* [[PTR1_CAST]])
 ; CHECK-NEXT:    ret void
 ;