diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/JumpThreading.cpp | 19 | ||||
| -rw-r--r-- | llvm/test/Transforms/JumpThreading/basic.ll | 34 |
2 files changed, 53 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp index 928fa3b1c6a..c79e756f572 100644 --- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp +++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp @@ -465,6 +465,25 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB, PredValueInfo &Result, return !Result.empty(); } + // Handle Cast instructions. Only see through Cast when the source operand is + // PHI or Cmp and the source type is i1 to save the compilation time. + if (CastInst *CI = dyn_cast<CastInst>(I)) { + Value *Source = CI->getOperand(0); + if (!Source->getType()->isIntegerTy(1)) + return false; + if (!isa<PHINode>(Source) && !isa<CmpInst>(Source)) + return false; + ComputeValueKnownInPredecessors(Source, BB, Result, Preference, CxtI); + if (Result.empty()) + return false; + + // Convert the known values. + for (auto &R : Result) + R.first = ConstantExpr::getCast(CI->getOpcode(), R.first, CI->getType()); + + return true; + } + PredValueInfoTy LHSVals, RHSVals; // Handle some boolean conditions. diff --git a/llvm/test/Transforms/JumpThreading/basic.ll b/llvm/test/Transforms/JumpThreading/basic.ll index 46c92bc1f57..14cd1fbe1c8 100644 --- a/llvm/test/Transforms/JumpThreading/basic.ll +++ b/llvm/test/Transforms/JumpThreading/basic.ll @@ -476,6 +476,40 @@ exit1: ; CHECK: } } +;;; Verify that we can handle constraint propagation through cast. +define i32 @test16(i1 %cond) { +Entry: +; CHECK-LABEL: @test16( + br i1 %cond, label %Merge, label %F1 + +; CHECK: Entry: +; CHECK-NEXT: br i1 %cond, label %F2, label %Merge + +F1: + %v1 = call i32 @f1() + br label %Merge + +Merge: + %B = phi i32 [0, %Entry], [%v1, %F1] + %M = icmp eq i32 %B, 0 + %M1 = zext i1 %M to i32 + %N = icmp eq i32 %M1, 0 + br i1 %N, label %T2, label %F2 + +; CHECK: Merge: +; CHECK-NOT: phi +; CHECK-NEXT: %v1 = call i32 @f1() + +T2: + %Q = call i32 @f2() + ret i32 %Q + +F2: + ret i32 %B +; CHECK: F2: +; CHECK-NEXT: phi i32 +} + ; In this test we check that block duplication is inhibited by the presence ; of a function with the 'noduplicate' attribute. |
