[AVX-512][InstCombine] Teach InstCombineCalls how to simplify demanded elements for...

These intrinsics don't read the upper bits of their second input. And the third input is the passthru for masking and that only uses the lower element as well.

llvm-svn: 289370

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index c50e829..3f666bc 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1775,6 +1775,37 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
     break;
   }
 
+  case Intrinsic::x86_avx512_mask_add_ss_round:
+  case Intrinsic::x86_avx512_mask_div_ss_round:
+  case Intrinsic::x86_avx512_mask_mul_ss_round:
+  case Intrinsic::x86_avx512_mask_sub_ss_round:
+  case Intrinsic::x86_avx512_mask_max_ss_round:
+  case Intrinsic::x86_avx512_mask_min_ss_round:
+  case Intrinsic::x86_avx512_mask_add_sd_round:
+  case Intrinsic::x86_avx512_mask_div_sd_round:
+  case Intrinsic::x86_avx512_mask_mul_sd_round:
+  case Intrinsic::x86_avx512_mask_sub_sd_round:
+  case Intrinsic::x86_avx512_mask_max_sd_round:
+  case Intrinsic::x86_avx512_mask_min_sd_round: {
+    // These intrinsics only demand the lowest element of the second and third
+    // input vector.
+    bool MadeChange = false;
+    Value *Arg1 = II->getArgOperand(1);
+    Value *Arg2 = II->getArgOperand(2);
+    unsigned VWidth = Arg1->getType()->getVectorNumElements();
+    if (Value *V = SimplifyDemandedVectorEltsLow(Arg1, VWidth, 1)) {
+      II->setArgOperand(1, V);
+      MadeChange = true;
+    }
+    if (Value *V = SimplifyDemandedVectorEltsLow(Arg2, VWidth, 1)) {
+      II->setArgOperand(2, V);
+      MadeChange = true;
+    }
+    if (MadeChange)
+      return II;
+    break;
+  }
+
   case Intrinsic::x86_sse41_round_ss:
   case Intrinsic::x86_sse41_round_sd: {
     // These intrinsics demand the upper elements of the first input vector and