RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2025-01-31 20:51:52 +01:00
Code Issues Projects Releases Wiki Activity

[BPF] fix a bug in BPFMISimplifyPatchable pass with -O0

Browse Source 
The recommended optimization level for BPF programs
is O2 since (1). BPF is running inside the kernel and
linux kernel won't work at -O0 level, and (2). Verifier
is not able to handle O0 code properly, e.g., potential
large stack size and a lot of spills.

But we should keep -O0 at least compiling.
This patch fixed a bug in BPFMISimplifyPatchable phase
where with -O0, a segmentation fault will happen for a
simple program like:
  int test(int a, int b) { return a + b; }

A test case is added to capture such a case.

Differential Revision: https://reviews.llvm.org/D73681
This commit is contained in:
Yonghong Song 2020-01-29 22:33:09 -08:00
parent f77176c4ec
commit 3b5deb36b6
2 changed files with 56 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
lib/Target/BPF/BPFMISimplifyPatchable.cpp
View File

@ -70,9 +70,10 @@ private:
public:
// Main entry point for this pass.
bool runOnMachineFunction(MachineFunction &MF) override {
if (!skipFunction(MF.getFunction())) {
initialize(MF);
}
if (skipFunction(MF.getFunction()))
return false;
initialize(MF);
return removeLD();
}
};

52
test/CodeGen/BPF/optnone-1.ll Normal file
View File

@ -0,0 +1,52 @@
; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
; Source Code:
; int test(int a, int b) { return a + b; }
; Compilation flag:
; clang -target bpf -g -S -emit-llvm test.c
; Function Attrs: noinline nounwind optnone
define dso_local i32 @test(i32 %a, i32 %b) #0 !dbg !7 {
entry:
%a.addr = alloca i32, align 4
%b.addr = alloca i32, align 4
store i32 %a, i32* %a.addr, align 4
call void @llvm.dbg.declare(metadata i32* %a.addr, metadata !11, metadata !DIExpression()), !dbg !12
store i32 %b, i32* %b.addr, align 4
call void @llvm.dbg.declare(metadata i32* %b.addr, metadata !13, metadata !DIExpression()), !dbg !14
%0 = load i32, i32* %a.addr, align 4, !dbg !15
%1 = load i32, i32* %b.addr, align 4, !dbg !16
%add = add nsw i32 %0, %1, !dbg !17
ret i32 %add, !dbg !18
}
; CHECK-LABEL: test
; Function Attrs: nounwind readnone speculatable
declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
attributes #0 = { noinline nounwind optnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { nounwind readnone speculatable}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5}
!llvm.ident = !{!6}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 11.0.0 (https://github.com/llvm/llvm-project.git 7f49dc496682e38335b204bbae371a0ca5057719)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/llvm")
!2 = !{}
!3 = !{i32 7, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{!"clang version 11.0.0 (https://github.com/llvm/llvm-project.git 7f49dc496682e38335b204bbae371a0ca5057719)"}
!7 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
!8 = !DISubroutineType(types: !9)
!9 = !{!10, !10, !10}
!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!11 = !DILocalVariable(name: "a", arg: 1, scope: !7, file: !1, line: 1, type: !10)
!12 = !DILocation(line: 1, column: 14, scope: !7)
!13 = !DILocalVariable(name: "b", arg: 2, scope: !7, file: !1, line: 1, type: !10)
!14 = !DILocation(line: 1, column: 21, scope: !7)
!15 = !DILocation(line: 1, column: 33, scope: !7)
!16 = !DILocation(line: 1, column: 37, scope: !7)
!17 = !DILocation(line: 1, column: 35, scope: !7)
!18 = !DILocation(line: 1, column: 26, scope: !7)