[llvm] r308618 - [DAG] Handle missing transform in fold of value extension case.

[Nirav Dave via llvm-commits]

Author: niravd
Date: Thu Jul 20 06:57:32 2017
New Revision: 308618

URL: http://llvm.org/viewvc/llvm-project?rev=308618&view=rev
Log:
[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

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/trunk/test/CodeGen/X86/avx512-mask-op.ll

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=308618&r1=308617&r2=308618&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Thu Jul 20 06:57:32 2017
@@ -7316,8 +7316,15 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SD
                                     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(SD
                                     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

Modified: llvm/trunk/test/CodeGen/X86/avx512-mask-op.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/avx512-mask-op.ll?rev=308618&r1=308617&r2=308618&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/avx512-mask-op.ll (original)
+++ llvm/trunk/test/CodeGen/X86/avx512-mask-op.ll Thu Jul 20 06:57:32 2017
@@ -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