diff options
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 14 | ||||
| -rw-r--r-- | test/Analysis/ScalarEvolution/fold.ll | 10 |
2 files changed, 23 insertions, 1 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index ce04188..7258fec 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -819,6 +819,20 @@ const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) return getTruncateOrZeroExtend(SZ->getOperand(), Ty); + // trunc(x1+x2+...+xN) --> trunc(x1)+trunc(x2)+...+trunc(xN) if we can + // eliminate all the truncates. + if (const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Op)) { + SmallVector<const SCEV *, 4> Operands; + bool hasTrunc = false; + for (unsigned i = 0, e = SA->getNumOperands(); i != e && !hasTrunc; ++i) { + const SCEV *S = getTruncateExpr(SA->getOperand(i), Ty); + hasTrunc = isa<SCEVTruncateExpr>(S); + Operands.push_back(S); + } + if (!hasTrunc) + return getAddExpr(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 202ddd4..f46c691 100644 --- a/test/Analysis/ScalarEvolution/fold.ll +++ b/test/Analysis/ScalarEvolution/fold.ll @@ -1,8 +1,16 @@ ; RUN: opt -analyze -scalar-evolution %s -S | FileCheck %s -define i16 @test(i8 %x) { +define i16 @test1(i8 %x) { %A = zext i8 %x to i12 %B = sext i12 %A to i16 ; CHECK: zext i8 %x to i16 ret i16 %B } + +define i8 @test2(i8 %x) { + %A = zext i8 %x to i16 + %B = add i16 %A, 1025 + %C = trunc i16 %B to i8 +; CHECK: (1 + %x) + ret i8 %C +} |