From d089c7ec3b320c83eb7fd7a6675b8d253278273c Mon Sep 17 00:00:00 2001 From: DianQK Date: Wed, 9 Aug 2023 04:50:30 +0800 Subject: [PATCH] [TailCallElim] Remove the readonly attribute of byval. When eliminating a tail call, we modify the values of the arguments. Therefore, if the byval parameter has a readonly attribute, we have to remove it. It is safe because, from the perspective of a caller, the byval parameter is always treated as "readonly," even if the readonly attribute is removed. Fixes #64289. Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D156793 Signed-off-by: fengting --- .../Scalar/TailRecursionElimination.cpp | 6 ++++ .../PhaseOrdering/pr64289-tce-adapt.ll | 28 +++++++++++++++++++ 2 files changed, 34 insertions(+) create mode 100644 llvm/test/Transforms/PhaseOrdering/pr64289-tce-adapt.ll diff --git a/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp b/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp index 27c04177e894..cbb96e657f0b 100644 --- a/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp +++ b/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp @@ -673,6 +673,12 @@ bool TailRecursionEliminator::eliminateCall(CallInst *CI) { for (unsigned I = 0, E = CI->arg_size(); I != E; ++I) { if (CI->isByValArgument(I)) { copyLocalTempOfByValueOperandIntoArguments(CI, I); + // When eliminating a tail call, we modify the values of the arguments. + // Therefore, if the byval parameter has a readonly attribute, we have to + // remove it. It is safe because, from the perspective of a caller, the + // byval parameter is always treated as "readonly," even if the readonly + // attribute is removed. + F.removeParamAttr(I, Attribute::ReadOnly); ArgumentPHIs[I]->addIncoming(F.getArg(I), BB); } else ArgumentPHIs[I]->addIncoming(CI->getArgOperand(I), BB); diff --git a/llvm/test/Transforms/PhaseOrdering/pr64289-tce-adapt.ll b/llvm/test/Transforms/PhaseOrdering/pr64289-tce-adapt.ll new file mode 100644 index 000000000000..e23e0be79ac1 --- /dev/null +++ b/llvm/test/Transforms/PhaseOrdering/pr64289-tce-adapt.ll @@ -0,0 +1,28 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py +; RUN: opt -S -O3 < %s | FileCheck %s + +; A miscompilation found on https://github.com/llvm/llvm-project/issues/64289. +; 1. PostOrderFunctionAttrsPass added readonly to the parameter. +; 2. TailCallElimPass modified the parameter but kept readonly. +; 3. LICMPass incorrectly hoisted the load instruction. + +define void @pr64289(ptr noalias byval(i64) %x) { +; CHECK-LABEL: @pr64289( +; CHECK-NOT: readonly +; CHECK-SAME: byval +; CHECK-NEXT: start: +; +start: + %new_x = alloca i64, align 8 + %x_val = load i64, ptr %x, align 8 + %is_zero = icmp eq i64 %x_val, 0 + br i1 %is_zero, label %end, label %recurse + +recurse: + store i64 0, ptr %new_x, align 8 + call void @pr64289(ptr %new_x) + br label %end + +end: + ret void +} -- Gitee