[InstCombine][X86][AVX] Add DemandedElts support for VPERMILPD/VPERMILPS instructions

Simplify a vpermilvar shuffle mask based on the elements of the mask that are actually demanded.

llvm-svn: 292209

2 files changed, 20 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index c68a5ca9134..8d896109e9f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -2347,10 +2347,20 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
   case Intrinsic::x86_avx512_vpermilvar_ps_512:
   case Intrinsic::x86_avx_vpermilvar_pd:
   case Intrinsic::x86_avx_vpermilvar_pd_256:
-  case Intrinsic::x86_avx512_vpermilvar_pd_512:
+  case Intrinsic::x86_avx512_vpermilvar_pd_512: {
     if (Value *V = simplifyX86vpermilvar(*II, *Builder))
       return replaceInstUsesWith(*II, V);
+
+    unsigned VWidth = II->getType()->getVectorNumElements();
+    APInt UndefElts(VWidth, 0);
+    APInt DemandedElts = APInt::getAllOnesValue(VWidth);
+    if (Value *V = SimplifyDemandedVectorElts(II, DemandedElts, UndefElts)) {
+      if (V != II)
+        return replaceInstUsesWith(*II, V);
+      return II;
+    }
     break;
+  }
 
   case Intrinsic::x86_avx2_permd:
   case Intrinsic::x86_avx2_permps:
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 95100d074b4..bf88a7517c1 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -1472,9 +1472,17 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
       break;
     }
 
+    // PSHUFB
     case Intrinsic::x86_ssse3_pshuf_b_128:
     case Intrinsic::x86_avx2_pshuf_b:
-    case Intrinsic::x86_avx512_pshuf_b_512: {
+    case Intrinsic::x86_avx512_pshuf_b_512:
+    // PERMILVAR
+    case Intrinsic::x86_avx_vpermilvar_ps:
+    case Intrinsic::x86_avx_vpermilvar_ps_256:
+    case Intrinsic::x86_avx512_vpermilvar_ps_512:
+    case Intrinsic::x86_avx_vpermilvar_pd:
+    case Intrinsic::x86_avx_vpermilvar_pd_256:
+    case Intrinsic::x86_avx512_vpermilvar_pd_512: {
       Value *Op1 = II->getArgOperand(1);
       TmpV = SimplifyDemandedVectorElts(Op1, DemandedElts, UndefElts,
                                         Depth + 1);