[llvm] 80aa9b0 - [PowerPC] stop reverse mem op generation for some cases.

[Chen Zheng via llvm-commits]

Author: Chen Zheng
Date: 2021-04-12T22:41:28-04:00
New Revision: 80aa9b0f7b3ebe53220a398b2939610d8a49e24b

URL: https://github.com/llvm/llvm-project/commit/80aa9b0f7b3ebe53220a398b2939610d8a49e24b
DIFF: https://github.com/llvm/llvm-project/commit/80aa9b0f7b3ebe53220a398b2939610d8a49e24b.diff

LOG: [PowerPC] stop reverse mem op generation for some cases.

We should consider the feeder user number when we do reverse memory
operation transformation. Otherwise, we may get negative impact.

Reviewed By: nemanjai

Differential Revision: https://reviews.llvm.org/D100166

Added: 
    

Modified: 
    llvm/lib/Target/PowerPC/PPCISelLowering.cpp
    llvm/test/CodeGen/PowerPC/vsx-shuffle-le-multiple-uses.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 30927bf88b7ce..48dba751a230d 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -14403,6 +14403,11 @@ SDValue PPCTargetLowering::combineVReverseMemOP(ShuffleVectorSDNode *SVN,
     return SDValue();
 
   if (LSBase->getOpcode() == ISD::LOAD) {
+    // If the load has more than one user except the shufflevector instruction,
+    // it is not profitable to replace the shufflevector with a reverse load.
+    if (!LSBase->hasOneUse())
+      return SDValue();
+
     SDLoc dl(SVN);
     SDValue LoadOps[] = {LSBase->getChain(), LSBase->getBasePtr()};
     return DAG.getMemIntrinsicNode(
@@ -14411,6 +14416,12 @@ SDValue PPCTargetLowering::combineVReverseMemOP(ShuffleVectorSDNode *SVN,
   }
 
   if (LSBase->getOpcode() == ISD::STORE) {
+    // If there are other uses of the shuffle, the swap cannot be avoided.
+    // Forcing the use of an X-Form (since swapped stores only have
+    // X-Forms) without removing the swap is unprofitable.
+    if (!SVN->hasOneUse())
+      return SDValue();
+
     SDLoc dl(LSBase);
     SDValue StoreOps[] = {LSBase->getChain(), SVN->getOperand(0),
                           LSBase->getBasePtr()};

diff  --git a/llvm/test/CodeGen/PowerPC/vsx-shuffle-le-multiple-uses.ll b/llvm/test/CodeGen/PowerPC/vsx-shuffle-le-multiple-uses.ll
index 6fbe8694f82df..d771b80bb9a94 100644
--- a/llvm/test/CodeGen/PowerPC/vsx-shuffle-le-multiple-uses.ll
+++ b/llvm/test/CodeGen/PowerPC/vsx-shuffle-le-multiple-uses.ll
@@ -7,8 +7,8 @@ define <2 x double> @loadHasMultipleUses(<2 x double>* %p1, <2 x double>* %p2) {
 ; CHECK-LABEL: loadHasMultipleUses:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    lxv 0, 0(3)
+; CHECK-NEXT:    xxswapd 34, 0
 ; CHECK-NEXT:    stxv 0, 0(4)
-; CHECK-NEXT:    lxvd2x 34, 0, 3
 ; CHECK-NEXT:    blr
   %v1 = load <2 x double>, <2 x double>* %p1
   store <2 x double> %v1, <2 x double>* %p2, align 16
@@ -19,10 +19,8 @@ define <2 x double> @loadHasMultipleUses(<2 x double>* %p1, <2 x double>* %p2) {
 define <2 x double> @storeHasMultipleUses(<2 x double> %v, <2 x double>* %p) {
 ; CHECK-LABEL: storeHasMultipleUses:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    xxswapd 0, 34
-; CHECK-NEXT:    addi 3, 5, 256
-; CHECK-NEXT:    stxvd2x 34, 0, 3
-; CHECK-NEXT:    xxlor 34, 0, 0
+; CHECK-NEXT:    xxswapd 34, 34
+; CHECK-NEXT:    stxv 34, 256(5)
 ; CHECK-NEXT:    blr
   %v1 = shufflevector <2 x double> %v, <2 x double> %v, <2 x i32> < i32 1, i32 0>
   %addr = getelementptr inbounds <2 x double>, <2 x double>* %p, i64 16