diff options
| -rw-r--r-- | llvm/lib/Analysis/ConstantFolding.cpp | 25 | ||||
| -rw-r--r-- | llvm/test/Analysis/ConstantFolding/funnel-shift.ll | 18 |
2 files changed, 31 insertions, 12 deletions
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp index f741f66d462..bbd812bf517 100644 --- a/llvm/lib/Analysis/ConstantFolding.cpp +++ b/llvm/lib/Analysis/ConstantFolding.cpp @@ -1389,6 +1389,8 @@ bool llvm::canConstantFoldCallTo(ImmutableCallSite CS, const Function *F) { case Intrinsic::ctpop: case Intrinsic::ctlz: case Intrinsic::cttz: + case Intrinsic::fshl: + case Intrinsic::fshr: case Intrinsic::fma: case Intrinsic::fmuladd: case Intrinsic::copysign: @@ -2081,6 +2083,29 @@ Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID, Type *Ty, } } + if (IntrinsicID == Intrinsic::fshl || IntrinsicID == Intrinsic::fshr) { + auto *C0 = dyn_cast<ConstantInt>(Operands[0]); + auto *C1 = dyn_cast<ConstantInt>(Operands[1]); + auto *C2 = dyn_cast<ConstantInt>(Operands[2]); + if (!(C0 && C1 && C2)) + return nullptr; + + // The shift amount is interpreted as modulo the bitwidth. If the shift + // amount is effectively 0, avoid UB due to oversized inverse shift below. + unsigned BitWidth = C0->getBitWidth(); + unsigned ShAmt = C2->getValue().urem(BitWidth); + bool IsRight = IntrinsicID == Intrinsic::fshr; + if (!ShAmt) + return IsRight ? C1 : C0; + + // (X << ShlAmt) | (Y >> LshrAmt) + const APInt &X = C0->getValue(); + const APInt &Y = C1->getValue(); + unsigned LshrAmt = IsRight ? ShAmt : BitWidth - ShAmt; + unsigned ShlAmt = !IsRight ? ShAmt : BitWidth - ShAmt; + return ConstantInt::get(Ty->getContext(), X.shl(ShlAmt) | Y.lshr(LshrAmt)); + } + return nullptr; } diff --git a/llvm/test/Analysis/ConstantFolding/funnel-shift.ll b/llvm/test/Analysis/ConstantFolding/funnel-shift.ll index 86a4d62a06e..8ccc714ae53 100644 --- a/llvm/test/Analysis/ConstantFolding/funnel-shift.ll +++ b/llvm/test/Analysis/ConstantFolding/funnel-shift.ll @@ -12,8 +12,7 @@ declare <4 x i8> @llvm.fshr.v4i8(<4 x i8>, <4 x i8>, <4 x i8>) define i32 @fshl_i32() { ; CHECK-LABEL: @fshl_i32( -; CHECK-NEXT: [[F:%.*]] = call i32 @llvm.fshl.i32(i32 305419896, i32 -1412567295, i32 5) -; CHECK-NEXT: ret i32 [[F]] +; CHECK-NEXT: ret i32 1183502101 ; %f = call i32 @llvm.fshl.i32(i32 305419896, i32 2882400001, i32 5) ret i32 %f @@ -24,8 +23,7 @@ define i32 @fshl_i32() { define i32 @fshr_i32() { ; CHECK-LABEL: @fshr_i32( -; CHECK-NEXT: [[F:%.*]] = call i32 @llvm.fshr.i32(i32 305419896, i32 -1412567295, i32 37) -; CHECK-NEXT: ret i32 [[F]] +; CHECK-NEXT: ret i32 -983666824 ; %f = call i32 @llvm.fshr.i32(i32 305419896, i32 2882400001, i32 37) ret i32 %f @@ -38,8 +36,7 @@ define i32 @fshr_i32() { define i7 @fshl_i7() { ; CHECK-LABEL: @fshl_i7( -; CHECK-NEXT: [[F:%.*]] = call i7 @llvm.fshl.i7(i7 -16, i7 -1, i7 9) -; CHECK-NEXT: ret i7 [[F]] +; CHECK-NEXT: ret i7 -61 ; %f = call i7 @llvm.fshl.i7(i7 112, i7 127, i7 9) ret i7 %f @@ -50,8 +47,7 @@ define i7 @fshl_i7() { define i7 @fshr_i7() { ; CHECK-LABEL: @fshr_i7( -; CHECK-NEXT: [[F:%.*]] = call i7 @llvm.fshr.i7(i7 -16, i7 -1, i7 16) -; CHECK-NEXT: ret i7 [[F]] +; CHECK-NEXT: ret i7 31 ; %f = call i7 @llvm.fshr.i7(i7 112, i7 127, i7 16) ret i7 %f @@ -65,8 +61,7 @@ define i7 @fshr_i7() { define <4 x i8> @fshl_v4i8() { ; CHECK-LABEL: @fshl_v4i8( -; CHECK-NEXT: [[F:%.*]] = call <4 x i8> @llvm.fshl.v4i8(<4 x i8> <i8 0, i8 -1, i8 16, i8 17>, <4 x i8> <i8 -1, i8 0, i8 85, i8 -86>, <4 x i8> <i8 0, i8 8, i8 9, i8 10>) -; CHECK-NEXT: ret <4 x i8> [[F]] +; CHECK-NEXT: ret <4 x i8> <i8 0, i8 -1, i8 32, i8 70> ; %f = call <4 x i8> @llvm.fshl.v4i8(<4 x i8> <i8 0, i8 -1, i8 16, i8 17>, <4 x i8> <i8 -1, i8 0, i8 85, i8 170>, <4 x i8> <i8 0, i8 8, i8 9, i8 10>) ret <4 x i8> %f @@ -80,8 +75,7 @@ define <4 x i8> @fshl_v4i8() { define <4 x i8> @fshr_v4i8() { ; CHECK-LABEL: @fshr_v4i8( -; CHECK-NEXT: [[F:%.*]] = call <4 x i8> @llvm.fshr.v4i8(<4 x i8> <i8 0, i8 -1, i8 16, i8 17>, <4 x i8> <i8 -1, i8 0, i8 85, i8 -86>, <4 x i8> <i8 0, i8 8, i8 9, i8 10>) -; CHECK-NEXT: ret <4 x i8> [[F]] +; CHECK-NEXT: ret <4 x i8> <i8 -1, i8 0, i8 42, i8 106> ; %f = call <4 x i8> @llvm.fshr.v4i8(<4 x i8> <i8 0, i8 -1, i8 16, i8 17>, <4 x i8> <i8 -1, i8 0, i8 85, i8 170>, <4 x i8> <i8 0, i8 8, i8 9, i8 10>) ret <4 x i8> %f |
