diff options
| -rw-r--r-- | lib/Transforms/IPO/GlobalOpt.cpp | 6 | ||||
| -rw-r--r-- | test/Transforms/GlobalOpt/zeroinitializer-gep-load.ll | 11 |
2 files changed, 17 insertions, 0 deletions
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp index a32e550..1522aa4 100644 --- a/lib/Transforms/IPO/GlobalOpt.cpp +++ b/lib/Transforms/IPO/GlobalOpt.cpp @@ -341,6 +341,12 @@ static bool CleanupConstantGlobalUsers(Value *V, Constant *Init, dyn_cast_or_null<ConstantExpr>(ConstantFoldInstruction(GEP, TD, TLI)); if (Init && CE && CE->getOpcode() == Instruction::GetElementPtr) SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE); + + // If the initializer is an all-null value and we have an inbounds GEP, + // we already know what the result of any load from that GEP is. + // TODO: Handle splats. + if (Init && isa<ConstantAggregateZero>(Init) && GEP->isInBounds()) + SubInit = Constant::getNullValue(GEP->getType()->getElementType()); } Changed |= CleanupConstantGlobalUsers(GEP, SubInit, TD, TLI); diff --git a/test/Transforms/GlobalOpt/zeroinitializer-gep-load.ll b/test/Transforms/GlobalOpt/zeroinitializer-gep-load.ll new file mode 100644 index 0000000..d613601 --- /dev/null +++ b/test/Transforms/GlobalOpt/zeroinitializer-gep-load.ll @@ -0,0 +1,11 @@ +; RUN: opt < %s -S -globalopt | FileCheck %s + +@zero = internal global [10 x i32] zeroinitializer + +define i32 @test1(i64 %idx) nounwind { + %arrayidx = getelementptr inbounds [10 x i32]* @zero, i64 0, i64 %idx + %l = load i32* %arrayidx + ret i32 %l +; CHECK: @test1 +; CHECK: ret i32 0 +} |