From df86d2d008b22f4e8cbed14f587acc611f687961 Mon Sep 17 00:00:00 2001
From: Nirav Dave <niravd@google.com>
Date: Thu, 20 Jul 2017 13:57:32 +0000
Subject: [PATCH] [DAG] Handle missing transform in fold of value extension
 case.

Summary:
When pushing an extension of a constant bitwise operator on a load
into the load, change other uses of the load value if they exist to
prevent the old load from persisting.

Reviewers: spatel, RKSimon, efriedma

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D35030

llvm-svn: 308618
---
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 14 ++++++++++++++
 llvm/test/CodeGen/X86/avx512-mask-op.ll       |  5 +----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 50cad23a00a2..3658544f085c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7316,8 +7316,15 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
                                     SDLoc(N0.getOperand(0)),
                                     N0.getOperand(0).getValueType(), ExtLoad);
         ExtendSetCCUses(SetCCs, Trunc, ExtLoad, DL, ISD::SIGN_EXTEND);
+        bool NoReplaceTruncAnd = !N0.hasOneUse();
         bool NoReplaceTrunc = SDValue(LN0, 0).hasOneUse();
         CombineTo(N, And);
+        // If N0 has multiple uses, change other uses as well.
+        if (NoReplaceTruncAnd) {
+          SDValue TruncAnd =
+              DAG.getNode(ISD::TRUNCATE, DL, N0.getValueType(), And);
+          CombineTo(N0.getNode(), TruncAnd);
+        }
         if (NoReplaceTrunc)
           DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
         else
@@ -7620,8 +7627,15 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
                                     SDLoc(N0.getOperand(0)),
                                     N0.getOperand(0).getValueType(), ExtLoad);
         ExtendSetCCUses(SetCCs, Trunc, ExtLoad, DL, ISD::ZERO_EXTEND);
+        bool NoReplaceTruncAnd = !N0.hasOneUse();
         bool NoReplaceTrunc = SDValue(LN0, 0).hasOneUse();
         CombineTo(N, And);
+        // If N0 has multiple uses, change other uses as well.
+        if (NoReplaceTruncAnd) {
+          SDValue TruncAnd =
+              DAG.getNode(ISD::TRUNCATE, DL, N0.getValueType(), And);
+          CombineTo(N0.getNode(), TruncAnd);
+        }
         if (NoReplaceTrunc)
           DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
         else
diff --git a/llvm/test/CodeGen/X86/avx512-mask-op.ll b/llvm/test/CodeGen/X86/avx512-mask-op.ll
index 6f4bf061a215..a0b5ae5822b1 100644
--- a/llvm/test/CodeGen/X86/avx512-mask-op.ll
+++ b/llvm/test/CodeGen/X86/avx512-mask-op.ll
@@ -1630,11 +1630,8 @@ define void @f1(i32 %c) {
 ; CHECK-LABEL: f1:
 ; CHECK:       ## BB#0: ## %entry
 ; CHECK-NEXT:    movzbl {{.*}}(%rip), %edi
-; CHECK-NEXT:    movb {{.*}}(%rip), %al
-; CHECK-NEXT:    notb %al
-; CHECK-NEXT:    andb $1, %al
-; CHECK-NEXT:    movb %al, {{.*}}(%rip)
 ; CHECK-NEXT:    xorl $1, %edi
+; CHECK-NEXT:    movb %dil, {{.*}}(%rip)
 ; CHECK-NEXT:    jmp _f2 ## TAILCALL
 entry:
   %.b1 = load i1, i1* @f1.v, align 4