diff options
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 14 | ||||
| -rw-r--r-- | test/Analysis/ScalarEvolution/fold.ll | 8 |
2 files changed, 22 insertions, 0 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 7258feca6c..424f74427b 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -833,6 +833,20 @@ const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, return getAddExpr(Operands, false, false); } + // trunc(x1*x2*...*xN) --> trunc(x1)*trunc(x2)*...*trunc(xN) if we can + // eliminate all the truncates. + if (const SCEVMulExpr *SM = dyn_cast<SCEVMulExpr>(Op)) { + SmallVector<const SCEV *, 4> Operands; + bool hasTrunc = false; + for (unsigned i = 0, e = SM->getNumOperands(); i != e && !hasTrunc; ++i) { + const SCEV *S = getTruncateExpr(SM->getOperand(i), Ty); + hasTrunc = isa<SCEVTruncateExpr>(S); + Operands.push_back(S); + } + if (!hasTrunc) + return getMulExpr(Operands, false, false); + } + // If the input value is a chrec scev, truncate the chrec's operands. if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) { SmallVector<const SCEV *, 4> Operands; diff --git a/test/Analysis/ScalarEvolution/fold.ll b/test/Analysis/ScalarEvolution/fold.ll index f46c691f46..3c1b6ae0fe 100644 --- a/test/Analysis/ScalarEvolution/fold.ll +++ b/test/Analysis/ScalarEvolution/fold.ll @@ -14,3 +14,11 @@ define i8 @test2(i8 %x) { ; CHECK: (1 + %x) ret i8 %C } + +define i8 @test3(i8 %x) { + %A = zext i8 %x to i16 + %B = mul i16 %A, 1027 + %C = trunc i16 %B to i8 +; CHECK: (3 * %x) + ret i8 %C +} |