[PATCH] D146034: [TTI] Treat AND/OR with widenable conditions as free of cost

[Max Kazantsev via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGd12af65d4626: [TTI] Treat AND/OR with widenable conditions as free of cost (authored by mkazantsev).

Changed prior to commit:
  https://reviews.llvm.org/D146034?vs=505035&id=505080#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D146034/new/

https://reviews.llvm.org/D146034

Files:
  llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
  llvm/test/Transforms/LoopUnroll/guard-cost-for-unrolling.ll


Index: llvm/test/Transforms/LoopUnroll/guard-cost-for-unrolling.ll
===================================================================
--- llvm/test/Transforms/LoopUnroll/guard-cost-for-unrolling.ll
+++ llvm/test/Transforms/LoopUnroll/guard-cost-for-unrolling.ll
@@ -2,7 +2,7 @@
 
 ; REQUIRES: asserts
 
-; FIXME: This test is needed to make sure that the guard cost remains the same,
+; This test is needed to make sure that the guard cost remains the same,
 ; independently on guard representation form (either intrinsic call or branch with
 ; widenable condition).
 
@@ -30,7 +30,7 @@
 
 define void @test_guard_as_branch(ptr %arr, i64 %n, i64 %bound) {
 ; CHECK-LABEL: Loop Unroll: F[test_guard_as_branch] Loop %loop
-; CHECK-NEXT:    Loop Size = 9
+; CHECK-NEXT:    Loop Size = 8
 ; CHECK-NEXT:    runtime unrolling with count: 2
 entry:
   br label %loop
Index: llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
===================================================================
--- llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -499,6 +499,14 @@
       TTI::OperandValueInfo Opd1Info, TTI::OperandValueInfo Opd2Info,
       ArrayRef<const Value *> Args,
       const Instruction *CxtI = nullptr) const {
+    // Widenable conditions will eventually lower into constants, so some
+    // operations with them will be trivially optimized away.
+    auto IsWidenableCondition = [](const Value *V) {
+      if (auto *II = dyn_cast<IntrinsicInst>(V))
+        if (II->getIntrinsicID() == Intrinsic::experimental_widenable_condition)
+          return true;
+      return false;
+    };
     // FIXME: A number of transformation tests seem to require these values
     // which seems a little odd for how arbitary there are.
     switch (Opcode) {
@@ -512,6 +520,11 @@
     case Instruction::URem:
       // FIXME: Unlikely to be true for CodeSize.
       return TTI::TCC_Expensive;
+    case Instruction::And:
+    case Instruction::Or:
+      if (any_of(Args, IsWidenableCondition))
+        return TTI::TCC_Free;
+      break;
     }
 
     // Assume a 3cy latency for fp arithmetic ops.


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D146034.505080.patch
Type: text/x-patch
Size: 2163 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20230314/4bc10aff/attachment.bin>