From 8dff60e96a0b3044628511b0e43a59788de56b9d Mon Sep 17 00:00:00 2001 From: Nadav Rotem Date: Mon, 13 Aug 2012 23:03:43 +0000 Subject: [PATCH] MemoryDependenceAnalysis attempts to find the first memory dependency for function calls. Currently, if GetLocation reports that it did not find a valid pointer (this is the case for volatile load/stores), we ignore the result. This patch adds code to handle the cases where we did not obtain a valid pointer. rdar://11872864 PR12899 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161802 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/MemoryDependenceAnalysis.cpp | 9 +++-- .../Analysis/GlobalsModRef/volatile-instrs.ll | 34 +++++++++++++++++++ 2 files changed, 41 insertions(+), 2 deletions(-) create mode 100644 test/Analysis/GlobalsModRef/volatile-instrs.ll diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp index 7fb154d68a2..059e57493b9 100644 --- a/lib/Analysis/MemoryDependenceAnalysis.cpp +++ b/lib/Analysis/MemoryDependenceAnalysis.cpp @@ -227,13 +227,18 @@ getCallSiteDependencyFrom(CallSite CS, bool isReadOnlyCall, // Otherwise if the two calls don't interact (e.g. InstCS is readnone) // keep scanning. - break; + continue; default: return MemDepResult::getClobber(Inst); } } + + // If we could not obtain a pointer for the instruction and the instruction + // touches memory then assume that this is a dependency. + if (MR != AliasAnalysis::NoModRef) + return MemDepResult::getClobber(Inst); } - + // No dependence found. If this is the entry block of the function, it is // unknown, otherwise it is non-local. if (BB != &BB->getParent()->getEntryBlock()) diff --git a/test/Analysis/GlobalsModRef/volatile-instrs.ll b/test/Analysis/GlobalsModRef/volatile-instrs.ll new file mode 100644 index 00000000000..49bce670b7f --- /dev/null +++ b/test/Analysis/GlobalsModRef/volatile-instrs.ll @@ -0,0 +1,34 @@ +; RUN: opt < %s -basicaa -dse -S | FileCheck %s + +target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128" +target triple = "x86_64-apple-macosx10.8.0" + +%struct.anon = type { i32, i32, i32 } +@b = global %struct.anon { i32 1, i32 0, i32 0 }, align 4 +@c = common global i32 0, align 4 +@a = common global %struct.anon zeroinitializer, align 4 +@.str = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1 + +declare i32 @printf(i8* nocapture, ...) nounwind +declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind + + +; Make sure that the initial memcpy call does not go away +; because the volatile load is in the way. PR12899 + +; CHECK: main_entry: +; CHECK-NEXT: tail call void @llvm.memcpy.p0i8.p0i8.i64 + +define i32 @main() nounwind uwtable ssp { +main_entry: + tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* bitcast (%struct.anon* @b to i8*), i8* bitcast (%struct.anon* @a to i8*), i64 12, i32 4, i1 false) + %0 = load volatile i32* getelementptr inbounds (%struct.anon* @b, i64 0, i32 0), align 4, !tbaa !0 + store i32 %0, i32* @c, align 4, !tbaa !0 + tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* bitcast (%struct.anon* @b to i8*), i8* bitcast (%struct.anon* @a to i8*), i64 12, i32 4, i1 false) nounwind + %call = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([4 x i8]* @.str, i64 0, i64 0), i32 %0) nounwind + ret i32 0 +} + +!0 = metadata !{metadata !"int", metadata !1} +!1 = metadata !{metadata !"omnipotent char", metadata !2} +!2 = metadata !{metadata !"Simple C/C++ TBAA"} -- 2.34.1