From 4bf015c035e4e5b63c7222dfb15ff274a5ed905c Mon Sep 17 00:00:00 2001 From: Richard Diamond Date: Mon, 2 Mar 2020 12:08:57 -0600 Subject: [PATCH] [AlignmentFromAssumptions] Fix a SCEV assertion resulting from address space differences. Summary: On targets with different pointer sizes, -alignment-from-assumptions could attempt to create SCEV expressions which use different effective SCEV types. The provided test illustrates the issue. In `getNewAlignment`, AASCEV would be the (only) alloca, which would have an effective SCEV type of i32. But PtrSCEV, the GEP in this case, due to being in the flat/default address space, will have an effective SCEV of i64. This patch resolves the issue by truncating PtrSCEV to AASCEV's effective type. Reviewers: hfinkel, jdoerfert Reviewed By: jdoerfert Subscribers: jvesely, nhaehnle, hiraditya, javed.absar, kerbowa, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D75471 --- .../Transforms/Scalar/AlignmentFromAssumptions.cpp | 5 ++++ .../AlignmentFromAssumptions/amdgpu-crash.ll | 33 ++++++++++++++++++++++ 2 files changed, 38 insertions(+) create mode 100644 llvm/test/Transforms/AlignmentFromAssumptions/amdgpu-crash.ll diff --git a/llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp b/llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp index 06deaf3..18715d8 100644 --- a/llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp +++ b/llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp @@ -127,6 +127,11 @@ static unsigned getNewAlignment(const SCEV *AASCEV, const SCEV *AlignSCEV, const SCEV *OffSCEV, Value *Ptr, ScalarEvolution *SE) { const SCEV *PtrSCEV = SE->getSCEV(Ptr); + // On a platform with 32-bit allocas, but 64-bit flat/global pointer sizes + // (*cough* AMDGPU), the effective SCEV type of AASCEV and PtrSCEV + // may disagree. Trunc/extend so they agree. + PtrSCEV = SE->getTruncateOrZeroExtend( + PtrSCEV, SE->getEffectiveSCEVType(AASCEV->getType())); const SCEV *DiffSCEV = SE->getMinusSCEV(PtrSCEV, AASCEV); // On 32-bit platforms, DiffSCEV might now have type i32 -- we've always diff --git a/llvm/test/Transforms/AlignmentFromAssumptions/amdgpu-crash.ll b/llvm/test/Transforms/AlignmentFromAssumptions/amdgpu-crash.ll new file mode 100644 index 0000000..065708a --- /dev/null +++ b/llvm/test/Transforms/AlignmentFromAssumptions/amdgpu-crash.ll @@ -0,0 +1,33 @@ +; Test that we don't crash. +; RUN: opt < %s -alignment-from-assumptions -S +; RUN: opt < %s -passes=alignment-from-assumptions -S + +target datalayout = "e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5-ni:7" + +%"core::str::CharIndices.29.66.90.114.138.149.165.173.181.197.205.213.229.387.398" = type { [0 x i64], i64, [0 x i64], { i8*, i8* }, [0 x i64] } +%"unwind::libunwind::_Unwind_Exception.9.51.75.99.123.147.163.171.179.195.203.211.227.385.396" = type { [0 x i64], i64, [0 x i64], void (i32, %"unwind::libunwind::_Unwind_Exception.9.51.75.99.123.147.163.171.179.195.203.211.227.385.396"*)*, [0 x i64], [6 x i64], [0 x i64] } +%"unwind::libunwind::_Unwind_Context.10.52.76.100.124.148.164.172.180.196.204.212.228.386.397" = type { [0 x i8] } + +define void @"_ZN44_$LT$$RF$T$u20$as$u20$core..fmt..Display$GT$3fmt17h7b1d039c7ff5e1feE"() { +start: + %_15.i.i = alloca %"core::str::CharIndices.29.66.90.114.138.149.165.173.181.197.205.213.229.387.398", align 8, addrspace(5) + br label %bb12.i.i + +bb12.i.i: ; preds = %start + %0 = addrspacecast %"core::str::CharIndices.29.66.90.114.138.149.165.173.181.197.205.213.229.387.398" addrspace(5)* %_15.i.i to %"core::str::CharIndices.29.66.90.114.138.149.165.173.181.197.205.213.229.387.398"* + %ptrint53.i.i = ptrtoint %"core::str::CharIndices.29.66.90.114.138.149.165.173.181.197.205.213.229.387.398"* %0 to i64 + %maskedptr54.i.i = and i64 %ptrint53.i.i, 7 + %maskcond55.i.i = icmp eq i64 %maskedptr54.i.i, 0 + call void @llvm.assume(i1 %maskcond55.i.i) + br i1 undef, label %bb20.i.i, label %bb3.i.i.i.i.i.preheader.i.i + +bb3.i.i.i.i.i.preheader.i.i: ; preds = %bb12.i.i + %1 = getelementptr inbounds %"core::str::CharIndices.29.66.90.114.138.149.165.173.181.197.205.213.229.387.398", %"core::str::CharIndices.29.66.90.114.138.149.165.173.181.197.205.213.229.387.398"* %0, i64 0, i32 0, i64 0 + store i64 0, i64* %1, align 8 + unreachable + +bb20.i.i: ; preds = %bb12.i.i + ret void +} + +declare void @llvm.assume(i1) -- 2.7.4