llvm/test/Transforms/GVN/no_speculative_loads_with_asan.ll
Dehao Chen 961ef79d43 Do not widen load for different variable in GVN.
Summary:
Widening load in GVN is too early because it will block other optimizations like PRE, LICM.

https://llvm.org/bugs/show_bug.cgi?id=29110

The SPECCPU2006 benchmark impact of this patch:

Reference: o2_nopatch
(1): o2_patched

           Benchmark             Base:Reference   (1)  
-------------------------------------------------------
spec/2006/fp/C++/444.namd                  25.2  -0.08%
spec/2006/fp/C++/447.dealII               45.92  +1.05%
spec/2006/fp/C++/450.soplex                41.7  -0.26%
spec/2006/fp/C++/453.povray               35.65  +1.68%
spec/2006/fp/C/433.milc                   23.79  +0.42%
spec/2006/fp/C/470.lbm                    41.88  -1.12%
spec/2006/fp/C/482.sphinx3                47.94  +1.67%
spec/2006/int/C++/471.omnetpp             22.46  -0.36%
spec/2006/int/C++/473.astar               21.19  +0.24%
spec/2006/int/C++/483.xalancbmk           36.09  -0.11%
spec/2006/int/C/400.perlbench             33.28  +1.35%
spec/2006/int/C/401.bzip2                 22.76  -0.04%
spec/2006/int/C/403.gcc                   32.36  +0.12%
spec/2006/int/C/429.mcf                   41.04  -0.41%
spec/2006/int/C/445.gobmk                 26.94  +0.04%
spec/2006/int/C/456.hmmer                  24.5  -0.20%
spec/2006/int/C/458.sjeng                    28  -0.46%
spec/2006/int/C/462.libquantum            55.25  +0.27%
spec/2006/int/C/464.h264ref               45.87  +0.72%

geometric mean                                   +0.23%

For most benchmarks, it's a wash, but we do see stable improvements on some benchmarks, e.g. 447,453,482,400.

Reviewers: davidxl, hfinkel, dberlin, sanjoy, reames

Subscribers: gberry, junbuml

Differential Revision: https://reviews.llvm.org/D24096

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281074 91177308-0d34-0410-b5e6-96231b3b80d8
2016-09-09 18:42:35 +00:00

56 lines
1.5 KiB
LLVM

; RUN: opt -O3 -S %s | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
declare noalias i8* @_Znam(i64) #1
define i32 @TestNoAsan() {
%1 = tail call noalias i8* @_Znam(i64 2)
%2 = getelementptr inbounds i8, i8* %1, i64 1
store i8 0, i8* %2, align 1
store i8 0, i8* %1, align 1
%3 = bitcast i8* %1 to i16*
%4 = load i16, i16* %3, align 4
%5 = icmp eq i16 %4, 0
br i1 %5, label %11, label %6
; <label>:6 ; preds = %0
%7 = getelementptr inbounds i8, i8* %1, i64 2
%8 = bitcast i8* %7 to i16*
%9 = load i16, i16* %8, align 2
%10 = sext i16 %9 to i32
br label %11
; <label>:11 ; preds = %0, %6
%12 = phi i32 [ %10, %6 ], [ 0, %0 ]
ret i32 %12
}
; CHECK-LABEL: @TestNoAsan
; CHECK: ret i32 0
define i32 @TestAsan() sanitize_address {
%1 = tail call noalias i8* @_Znam(i64 2)
%2 = getelementptr inbounds i8, i8* %1, i64 1
store i8 0, i8* %2, align 1
store i8 0, i8* %1, align 1
%3 = bitcast i8* %1 to i16*
%4 = load i16, i16* %3, align 4
%5 = icmp eq i16 %4, 0
br i1 %5, label %11, label %6
; <label>:6 ; preds = %0
%7 = getelementptr inbounds i8, i8* %1, i64 2
%8 = bitcast i8* %7 to i16*
%9 = load i16, i16* %8, align 2
%10 = sext i16 %9 to i32
br label %11
; <label>:11 ; preds = %0, %6
%12 = phi i32 [ %10, %6 ], [ 0, %0 ]
ret i32 %12
}
; CHECK-LABEL: @TestAsan
; CHECK-NOT: %[[LOAD:[^ ]+]] = load i32
; CHECK: {{.*}} = phi