Index: llvm/lib/Transforms/Scalar/GVNHoist.cpp =================================================================== --- llvm/lib/Transforms/Scalar/GVNHoist.cpp +++ llvm/lib/Transforms/Scalar/GVNHoist.cpp @@ -584,21 +584,13 @@ if (auto *St = dyn_cast(Repl)) { Gep = dyn_cast(St->getPointerOperand()); Val = dyn_cast(St->getValueOperand()); + // Check that the stored value is available. + if (Val && !allOperandsAvailable(Val, HoistPt)) + return false; } - if (!Gep) - return false; - - // PHIs may only be inserted at the start of a block. - if (Val && isa(Val)) - return false; - // Check whether we can compute the Gep at HoistPt. - if (!allOperandsAvailable(Gep, HoistPt)) - return false; - - // Also check that the stored value is available. - if (Val && !allOperandsAvailable(Val, HoistPt)) + if (!Gep || !allOperandsAvailable(Gep, HoistPt)) return false; // Copy the gep before moving the ld/st. @@ -618,8 +610,8 @@ } Repl->replaceUsesOfWith(Gep, ClonedGep); - // Also copy Val. - if (Val) { + // Also copy Val when it is a GEP. + if (Val && isa(Val)) { Instruction *ClonedVal = Val->clone(); ClonedVal->insertBefore(HoistPt->getTerminator()); // Conservatively discard any optimization hints, they may differ on the Index: llvm/test/Transforms/GVN/hoist-pr28606.ll =================================================================== --- /dev/null +++ llvm/test/Transforms/GVN/hoist-pr28606.ll @@ -0,0 +1,50 @@ +; RUN: opt -gvn-hoist -S < %s | FileCheck %s + +target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32" +target triple = "i686-pc-windows-msvc18.0.0" + +%struct.S = type { i8* } + +declare void @f(<{ %struct.S }>* inalloca) + + +; Check that we don't clone the %x alloca and insert it in the live range of +; %argmem, which would break the inalloca contract. +; +; CHECK-LABEL: @test +; CHECK: alloca i8 +; CHECK: stacksave +; CHECK: alloca inalloca +; CHECK-NOT: alloca i8 + +; Check that store instructions are hoisted. +; CHECK: store i8 +; CHECK-NOT: store i8 +; CHECK: stackrestore + +define void @test(i1 %b) { +entry: + %x = alloca i8 + %inalloca.save = call i8* @llvm.stacksave() + %argmem = alloca inalloca <{ %struct.S }>, align 4 + %0 = getelementptr inbounds <{ %struct.S }>, <{ %struct.S }>* %argmem, i32 0, i32 0 + br i1 %b, label %true, label %false + +true: + %p = getelementptr inbounds %struct.S, %struct.S* %0, i32 0, i32 0 + store i8* %x, i8** %p, align 4 + br label %exit + +false: + %p2 = getelementptr inbounds %struct.S, %struct.S* %0, i32 0, i32 0 + store i8* %x, i8** %p2, align 4 + br label %exit + +exit: + call void @f(<{ %struct.S }>* inalloca %argmem) + call void @llvm.stackrestore(i8* %inalloca.save) + ret void +} + +declare i8* @llvm.stacksave() +declare void @llvm.stackrestore(i8*) Index: llvm/test/Transforms/GVN/pr28626.ll =================================================================== --- llvm/test/Transforms/GVN/pr28626.ll +++ llvm/test/Transforms/GVN/pr28626.ll @@ -38,5 +38,5 @@ ; CHECK: %[[gep0:.*]] = getelementptr inbounds i1, i1* %[[load]], i64 0 ; CHECK: store i1 %[[phi]], i1* %[[gep0]], align 4 -; CHECK: %[[gep1:.*]] = getelementptr inbounds i1, i1* %[[load]], i64 0 -; CHECK: store i1 %[[phi]], i1* %[[gep1]], align 4 +; Check that store instructions are hoisted. +; CHECK-NOT: store