diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp --- a/llvm/lib/Transforms/Scalar/SROA.cpp +++ b/llvm/lib/Transforms/Scalar/SROA.cpp @@ -1688,15 +1688,17 @@ bool IsThen = SuccBB == HeadBI->getSuccessor(0); int SuccIdx = IsThen ? 0 : 1; auto *NewMemOpBB = SuccBB == Tail ? Head : SuccBB; + auto &CondMemOp = cast(*I.clone()); if (NewMemOpBB != Head) { NewMemOpBB->setName(Head->getName() + (IsThen ? ".then" : ".else")); if (isa(I)) ++NumLoadsPredicated; else ++NumStoresPredicated; - } else + } else { + CondMemOp.dropUBImplyingAttrsAndUnknownMetadata(); ++NumLoadsSpeculated; - auto &CondMemOp = cast(*I.clone()); + } CondMemOp.insertBefore(NewMemOpBB->getTerminator()); Value *Ptr = SI.getOperand(1 + SuccIdx); if (auto *PtrTy = Ptr->getType(); diff --git a/llvm/test/Transforms/SROA/select-load.ll b/llvm/test/Transforms/SROA/select-load.ll --- a/llvm/test/Transforms/SROA/select-load.ll +++ b/llvm/test/Transforms/SROA/select-load.ll @@ -409,7 +409,31 @@ ret i32 %r } +; When promoting speculative instruction, metadata that may trigger immediate UB should be dropped. +define void @load_of_select_with_noundef_nonnull(ptr %buffer, i1 %b) { +; CHECK-PRESERVE-CFG-LABEL: @load_of_select_with_noundef_nonnull( +; CHECK-PRESERVE-CFG-NEXT: [[UB_PTR:%.*]] = alloca ptr, align 8 +; CHECK-PRESERVE-CFG-NEXT: [[SELECT_PTR:%.*]] = select i1 [[B:%.*]], ptr [[BUFFER:%.*]], ptr [[UB_PTR]] +; CHECK-PRESERVE-CFG-NEXT: [[LOAD_PTR:%.*]] = load ptr, ptr [[SELECT_PTR]], align 8, !nonnull !1, !noundef !1 +; CHECK-PRESERVE-CFG-NEXT: ret void +; +; CHECK-MODIFY-CFG-LABEL: @load_of_select_with_noundef_nonnull( +; CHECK-MODIFY-CFG-NEXT: br i1 [[B:%.*]], label [[DOTTHEN:%.*]], label [[DOTCONT:%.*]] +; CHECK-MODIFY-CFG: .then: +; CHECK-MODIFY-CFG-NEXT: [[LOAD_PTR_THEN_VAL:%.*]] = load ptr, ptr [[BUFFER:%.*]], align 8, !nonnull !2, !noundef !2 +; CHECK-MODIFY-CFG-NEXT: br label [[DOTCONT]] +; CHECK-MODIFY-CFG: .cont: +; CHECK-MODIFY-CFG-NEXT: [[LOAD_PTR:%.*]] = phi ptr [ [[LOAD_PTR_THEN_VAL]], [[DOTTHEN]] ], [ undef, [[TMP0:%.*]] ] +; CHECK-MODIFY-CFG-NEXT: ret void +; + %ub_ptr = alloca ptr + %select_ptr = select i1 %b, ptr %buffer, ptr %ub_ptr + %load_ptr = load ptr, ptr %select_ptr, !nonnull !1, !noundef !1 + ret void +} + !0 = !{!"branch_weights", i32 1, i32 99} +!1 = !{} ; Ensure that the branch metadata is reversed to match the reversals above.