[PATCH] D43446: [X86] Correct SHRUNKBLEND creation to work correctly when there are multiple uses of the condition.

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This revision was automatically updated to reflect the committed changes.
Closed by commit rL325604: [X86] Correct SHRUNKBLEND creation to work correctly when there are multiple… (authored by ctopper, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D43446?vs=134841&id=135090#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D43446

Files:
  llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
  llvm/trunk/test/CodeGen/X86/vselect.ll


Index: llvm/trunk/test/CodeGen/X86/vselect.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/vselect.ll
+++ llvm/trunk/test/CodeGen/X86/vselect.ll
@@ -503,8 +503,6 @@
 ; SSE41-LABEL: shrunkblend_2uses:
 ; SSE41:       # %bb.0:
 ; SSE41-NEXT:    psllq $63, %xmm0
-; SSE41-NEXT:    psrad $31, %xmm0
-; SSE41-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[1,1,3,3]
 ; SSE41-NEXT:    blendvpd %xmm0, %xmm1, %xmm2
 ; SSE41-NEXT:    blendvpd %xmm0, %xmm3, %xmm4
 ; SSE41-NEXT:    paddq %xmm2, %xmm4
@@ -514,8 +512,6 @@
 ; AVX-LABEL: shrunkblend_2uses:
 ; AVX:       # %bb.0:
 ; AVX-NEXT:    vpsllq $63, %xmm0, %xmm0
-; AVX-NEXT:    vpxor %xmm5, %xmm5, %xmm5
-; AVX-NEXT:    vpcmpgtq %xmm0, %xmm5, %xmm0
 ; AVX-NEXT:    vblendvpd %xmm0, %xmm1, %xmm2, %xmm1
 ; AVX-NEXT:    vblendvpd %xmm0, %xmm3, %xmm4, %xmm0
 ; AVX-NEXT:    vpaddq %xmm0, %xmm1, %xmm0
Index: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
@@ -31910,46 +31910,38 @@
     if (VT.is512BitVector())
       return SDValue();
 
-    assert(BitWidth >= 8 && BitWidth <= 64 && "Invalid mask size");
-    APInt DemandedMask(APInt::getSignMask(BitWidth));
-    KnownBits Known;
-    TargetLowering::TargetLoweringOpt TLO(DAG, !DCI.isBeforeLegalize(),
-                                          !DCI.isBeforeLegalizeOps());
-    if (TLI.SimplifyDemandedBits(Cond, DemandedMask, Known, TLO)) {
-      // If we changed the computation somewhere in the DAG, this change will
-      // affect all users of Cond. Make sure it is fine and update all the nodes
-      // so that we do not use the generic VSELECT anymore. Otherwise, we may
-      // perform wrong optimizations as we messed with the actual expectation
-      // for the vector boolean values.
-      if (Cond != TLO.Old) {
-        // Check all uses of the condition operand to check whether it will be
-        // consumed by non-BLEND instructions. Those may require that all bits
-        // are set properly.
-        for (SDNode::use_iterator UI = Cond->use_begin(), UE = Cond->use_end();
-             UI != UE; ++UI) {
-          // TODO: Add other opcodes eventually lowered into BLEND.
-          if (UI->getOpcode() != ISD::VSELECT || UI.getOperandNo() != 0)
-            return SDValue();
-        }
+    bool CanShrinkCond = true;
+    for (SDNode::use_iterator UI = Cond->use_begin(), UE = Cond->use_end();
+         UI != UE; ++UI) {
+      // TODO: Add other opcodes eventually lowered into BLEND.
+      if (UI->getOpcode() != ISD::VSELECT || UI.getOperandNo() != 0) {
+        CanShrinkCond = false;
+        break;
+      }
+    }
 
-        // Update all users of the condition before committing the change, so
-        // that the VSELECT optimizations that expect the correct vector boolean
-        // value will not be triggered.
+    if (CanShrinkCond) {
+      assert(BitWidth >= 8 && BitWidth <= 64 && "Invalid mask size");
+      APInt DemandedMask(APInt::getSignMask(BitWidth));
+      KnownBits Known;
+      TargetLowering::TargetLoweringOpt TLO(DAG, !DCI.isBeforeLegalize(),
+                                            !DCI.isBeforeLegalizeOps());
+      if (TLI.SimplifyDemandedBits(Cond, DemandedMask, Known, TLO, 0,
+                                   /*AssumeSingleUse*/true)) {
+        // If we changed the computation somewhere in the DAG, this change will
+        // affect all users of Cond. Update all the nodes so that we do not use
+        // the generic VSELECT anymore. Otherwise, we may perform wrong
+        // optimizations as we messed with the actual expectation for the vector
+        // boolean values.
         for (SDNode *U : Cond->uses()) {
           SDValue SB = DAG.getNode(X86ISD::SHRUNKBLEND, SDLoc(U),
                                    U->getValueType(0), Cond, U->getOperand(1),
                                    U->getOperand(2));
           DAG.ReplaceAllUsesOfValueWith(SDValue(U, 0), SB);
         }
         DCI.CommitTargetLoweringOpt(TLO);
-        return SDValue();
+        return SDValue(N, 0);
       }
-      // Only Cond (rather than other nodes in the computation chain) was
-      // changed. Change the condition just for N to keep the opportunity to
-      // optimize all other users their own way.
-      SDValue SB = DAG.getNode(X86ISD::SHRUNKBLEND, DL, VT, TLO.New, LHS, RHS);
-      DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), SB);
-      return SDValue();
     }
   }
 


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