diff options
| -rw-r--r-- | lib/Transforms/Utils/SimplifyCFG.cpp | 28 | ||||
| -rw-r--r-- | test/Transforms/SimplifyCFG/switch_create.ll | 36 |
2 files changed, 63 insertions, 1 deletions
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp index 6d12f7a..d8878f2 100644 --- a/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/lib/Transforms/Utils/SimplifyCFG.cpp @@ -40,12 +40,14 @@ #include "llvm/Support/ConstantRange.h" #include "llvm/Support/Debug.h" #include "llvm/Support/NoFolder.h" +#include "llvm/Support/PatternMatch.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" #include <algorithm> #include <map> #include <set> using namespace llvm; +using namespace PatternMatch; static cl::opt<unsigned> PHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(1), @@ -432,7 +434,24 @@ GatherConstantCompares(Value *V, std::vector<ConstantInt*> &Vals, Value *&Extra, // If this is an icmp against a constant, handle this as one of the cases. if (ICmpInst *ICI = dyn_cast<ICmpInst>(I)) { if (ConstantInt *C = GetConstantInt(I->getOperand(1), TD)) { + Value *RHSVal; + ConstantInt *RHSC; + if (ICI->getPredicate() == (isEQ ? ICmpInst::ICMP_EQ:ICmpInst::ICMP_NE)) { + // (x & ~2^x) == y --> x == y || x == y|2^x + // This undoes a transformation done by instcombine to fuse 2 compares. + if (match(ICI->getOperand(0), + m_And(m_Value(RHSVal), m_ConstantInt(RHSC)))) { + APInt Not = ~RHSC->getValue(); + if (Not.isPowerOf2()) { + Vals.push_back(C); + Vals.push_back( + ConstantInt::get(C->getContext(), C->getValue() | Not)); + UsedICmps++; + return RHSVal; + } + } + UsedICmps++; Vals.push_back(C); return I->getOperand(0); @@ -443,6 +462,13 @@ GatherConstantCompares(Value *V, std::vector<ConstantInt*> &Vals, Value *&Extra, ConstantRange Span = ConstantRange::makeICmpRegion(ICI->getPredicate(), C->getValue()); + // Shift the range if the compare is fed by an add. This is the range + // compare idiom as emitted by instcombine. + bool hasAdd = + match(I->getOperand(0), m_Add(m_Value(RHSVal), m_ConstantInt(RHSC))); + if (hasAdd) + Span = Span.subtract(RHSC->getValue()); + // If this is an and/!= check then we want to optimize "x ugt 2" into // x != 0 && x != 1. if (!isEQ) @@ -455,7 +481,7 @@ GatherConstantCompares(Value *V, std::vector<ConstantInt*> &Vals, Value *&Extra, for (APInt Tmp = Span.getLower(); Tmp != Span.getUpper(); ++Tmp) Vals.push_back(ConstantInt::get(V->getContext(), Tmp)); UsedICmps++; - return I->getOperand(0); + return hasAdd ? RHSVal : I->getOperand(0); } return 0; } diff --git a/test/Transforms/SimplifyCFG/switch_create.ll b/test/Transforms/SimplifyCFG/switch_create.ll index 546cc75..9d4e319 100644 --- a/test/Transforms/SimplifyCFG/switch_create.ll +++ b/test/Transforms/SimplifyCFG/switch_create.ll @@ -479,3 +479,39 @@ return: ; CHECK: ret void } +define void @test18(i32 %arg) { +bb: + %tmp = and i32 %arg, -2 + %tmp1 = icmp eq i32 %tmp, 8 + %tmp2 = icmp eq i32 %arg, 10 + %tmp3 = or i1 %tmp1, %tmp2 + %tmp4 = icmp eq i32 %arg, 11 + %tmp5 = or i1 %tmp3, %tmp4 + %tmp6 = icmp eq i32 %arg, 12 + %tmp7 = or i1 %tmp5, %tmp6 + br i1 %tmp7, label %bb19, label %bb8 + +bb8: ; preds = %bb + %tmp9 = add i32 %arg, -13 + %tmp10 = icmp ult i32 %tmp9, 2 + %tmp11 = icmp eq i32 %arg, 16 + %tmp12 = or i1 %tmp10, %tmp11 + %tmp13 = icmp eq i32 %arg, 17 + %tmp14 = or i1 %tmp12, %tmp13 + %tmp15 = icmp eq i32 %arg, 18 + %tmp16 = or i1 %tmp14, %tmp15 + %tmp17 = icmp eq i32 %arg, 15 + %tmp18 = or i1 %tmp16, %tmp17 + br i1 %tmp18, label %bb19, label %bb20 + +bb19: ; preds = %bb8, %bb + tail call void @foo1() + br label %bb20 + +bb20: ; preds = %bb19, %bb8 + ret void + +; CHECK: @test18 +; CHECK: %arg.off = add i32 %arg, -8 +; CHECK: icmp ult i32 %arg.off, 11 +} |