[PATCH] D111864: [AMDGPU] Avoid redundant calls to numBits in AMDGPUCodeGenPrepare::replaceMulWithMul24().

[Abinav Puthan Purayil via Phabricator via llvm-commits]

abinavpp created this revision.
abinavpp added reviewers: arsenm, foad, rampitec.
Herald added subscribers: kerbowa, hiraditya, t-tye, tpr, dstuttard, yaxunl, nhaehnle, jvesely, kzhuravl.
abinavpp requested review of this revision.
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The isU24() and isI24() calls numBits to make its decision. This change
replaces them with the internal numBits call so that we can use its
result for the > 32 bit width cases.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D111864

Files:
  llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp


Index: llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp
@@ -151,8 +151,6 @@
 
   unsigned numBitsUnsigned(Value *Op, unsigned ScalarSize) const;
   unsigned numBitsSigned(Value *Op, unsigned ScalarSize) const;
-  bool isI24(Value *V, unsigned ScalarSize) const;
-  bool isU24(Value *V, unsigned ScalarSize) const;
 
   /// Replace mul instructions with llvm.amdgcn.mul.u24 or llvm.amdgcn.mul.s24.
   /// SelectionDAG has an issue where an and asserting the bits are known
@@ -454,16 +452,6 @@
   return ScalarSize - ComputeNumSignBits(Op, *DL, 0, AC);
 }
 
-bool AMDGPUCodeGenPrepare::isI24(Value *V, unsigned ScalarSize) const {
-  return ScalarSize >= 24 && // Types less than 24-bit should be treated
-                                     // as unsigned 24-bit values.
-    numBitsSigned(V, ScalarSize) < 24;
-}
-
-bool AMDGPUCodeGenPrepare::isU24(Value *V, unsigned ScalarSize) const {
-  return numBitsUnsigned(V, ScalarSize) <= 24;
-}
-
 static void extractValues(IRBuilder<> &Builder,
                           SmallVectorImpl<Value *> &Values, Value *V) {
   auto *VT = dyn_cast<FixedVectorType>(V->getType());
@@ -509,23 +497,26 @@
 
   Intrinsic::ID IntrID = Intrinsic::not_intrinsic;
 
-  if (ST->hasMulU24() && isU24(LHS, Size) && isU24(RHS, Size)) {
+  unsigned LHSBits = 0, RHSBits = 0;
+
+  if (ST->hasMulU24() && (LHSBits = numBitsUnsigned(LHS, Size)) <= 24 &&
+      (RHSBits = numBitsUnsigned(RHS, Size)) <= 24) {
     // The mul24 instruction yields the low-order 32 bits. If the original
     // result and the destination is wider than 32 bits, the mul24 would
     // truncate the result.
-    if (Size > 32 &&
-        numBitsUnsigned(LHS, Size) + numBitsUnsigned(RHS, Size) > 32) {
+    if (Size > 32 && LHSBits + RHSBits > 32)
       return false;
-    }
 
     IntrID = Intrinsic::amdgcn_mul_u24;
-  } else if (ST->hasMulI24() && isI24(LHS, Size) && isI24(RHS, Size)) {
+  } else if (ST->hasMulI24() &&
+             Size >= 24 && // Types less than 24-bit should be treated as u24.
+             (LHSBits = numBitsSigned(LHS, Size)) < 24 &&
+             (RHSBits = numBitsSigned(RHS, Size)) < 24) {
     // The original result is positive if its destination is wider than 32 bits
     // and its highest set bit is at bit 31. Generating mul24 and sign-extending
     // it would yield a negative value.
-    if (Size > 32 && numBitsSigned(LHS, Size) + numBitsSigned(RHS, Size) > 30) {
+    if (Size > 32 && LHSBits + RHSBits > 30)
       return false;
-    }
 
     IntrID = Intrinsic::amdgcn_mul_i24;
   } else


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