1228becf7d
This patch deduces `noundef` attributes for return values. IIUC, a function returns `noundef` values iff all of its return values are guaranteed not to be `undef` or `poison`. Definition of `noundef` from LangRef: ``` noundef This attribute applies to parameters and return values. If the value representation contains any undefined or poison bits, the behavior is undefined. Note that this does not refer to padding introduced by the type’s storage representation. ``` Alive2: https://alive2.llvm.org/ce/z/g8Eis6 Compile-time impact: http://llvm-compile-time-tracker.com/compare.php?from=30dcc33c4ea3ab50397a7adbe85fe977d4a400bd&to=c5e8738d4bfbf1e97e3f455fded90b791f223d74&stat=instructions:u |stage1-O3|stage1-ReleaseThinLTO|stage1-ReleaseLTO-g|stage1-O0-g|stage2-O3|stage2-O0-g|stage2-clang| |--|--|--|--|--|--|--| |+0.01%|+0.01%|-0.01%|+0.01%|+0.03%|-0.04%|+0.01%| The motivation of this patch is to reduce the number of `freeze` insts and enable more optimizations.
145 lines
5.6 KiB
LLVM
145 lines
5.6 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
|
|
; RUN: opt -O2 -S < %s | FileCheck %s
|
|
;
|
|
; Source code:
|
|
; typedef unsigned long u64;
|
|
; void foo(char *data, int idx, u64 *);
|
|
; int test(int len, char *data) {
|
|
; if (len < 100) {
|
|
; for (int i = 1; i < len; i++) {
|
|
; u64 d[1];
|
|
; d[0] = data[0] ?: '0';
|
|
; foo("%c", i, d);
|
|
; }
|
|
; }
|
|
; return 0;
|
|
; }
|
|
; Compilation flag:
|
|
; clang -target bpf -O2 -S -emit-llvm -Xclang -disable-llvm-passes test.c
|
|
|
|
; ModuleID = 'test.c'
|
|
source_filename = "test.c"
|
|
target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128"
|
|
target triple = "bpf"
|
|
|
|
@.str = private unnamed_addr constant [3 x i8] c"%c\00", align 1
|
|
|
|
; Function Attrs: nounwind
|
|
define dso_local i32 @test(i32 %len, ptr %data) #0 {
|
|
; CHECK-LABEL: define dso_local noundef i32 @test(
|
|
; CHECK-SAME: i32 [[LEN:%.*]], ptr nocapture readonly [[DATA:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
|
|
; CHECK-NEXT: entry:
|
|
; CHECK-NEXT: [[D:%.*]] = alloca [1 x i64], align 8
|
|
; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[LEN]], -2
|
|
; CHECK-NEXT: [[OR_COND:%.*]] = icmp ult i32 [[TMP0]], 98
|
|
; CHECK-NEXT: br i1 [[OR_COND]], label [[FOR_BODY:%.*]], label [[IF_END:%.*]]
|
|
; CHECK: for.body:
|
|
; CHECK-NEXT: [[I_05:%.*]] = phi i32 [ [[INC:%.*]], [[FOR_BODY]] ], [ 1, [[ENTRY:%.*]] ]
|
|
; CHECK-NEXT: call void @llvm.lifetime.start.p0(i64 8, ptr nonnull [[D]]) #[[ATTR3:[0-9]+]]
|
|
; CHECK-NEXT: [[TMP1:%.*]] = load i8, ptr [[DATA]], align 1, !tbaa [[TBAA3:![0-9]+]]
|
|
; CHECK-NEXT: [[TOBOOL_NOT:%.*]] = icmp eq i8 [[TMP1]], 0
|
|
; CHECK-NEXT: [[NARROW:%.*]] = select i1 [[TOBOOL_NOT]], i8 48, i8 [[TMP1]]
|
|
; CHECK-NEXT: [[CONV2:%.*]] = sext i8 [[NARROW]] to i64
|
|
; CHECK-NEXT: store i64 [[CONV2]], ptr [[D]], align 8, !tbaa [[TBAA6:![0-9]+]]
|
|
; CHECK-NEXT: call void @foo(ptr nonnull @.str, i32 [[I_05]], ptr nonnull [[D]]) #[[ATTR3]]
|
|
; CHECK-NEXT: call void @llvm.lifetime.end.p0(i64 8, ptr nonnull [[D]]) #[[ATTR3]]
|
|
; CHECK-NEXT: [[INC]] = add nuw nsw i32 [[I_05]], 1
|
|
; CHECK-NEXT: [[EXITCOND_NOT:%.*]] = icmp eq i32 [[INC]], [[LEN]]
|
|
; CHECK-NEXT: br i1 [[EXITCOND_NOT]], label [[IF_END]], label [[FOR_BODY]], !llvm.loop [[LOOP8:![0-9]+]]
|
|
; CHECK: if.end:
|
|
; CHECK-NEXT: ret i32 0
|
|
;
|
|
entry:
|
|
%len.addr = alloca i32, align 4
|
|
%data.addr = alloca ptr, align 8
|
|
%i = alloca i32, align 4
|
|
%d = alloca [1 x i64], align 8
|
|
store i32 %len, ptr %len.addr, align 4, !tbaa !3
|
|
store ptr %data, ptr %data.addr, align 8, !tbaa !7
|
|
%0 = load i32, ptr %len.addr, align 4, !tbaa !3
|
|
%cmp = icmp slt i32 %0, 100
|
|
br i1 %cmp, label %if.then, label %if.end
|
|
|
|
if.then: ; preds = %entry
|
|
call void @llvm.lifetime.start.p0(i64 4, ptr %i) #3
|
|
store i32 1, ptr %i, align 4, !tbaa !3
|
|
br label %for.cond
|
|
|
|
for.cond: ; preds = %for.inc, %if.then
|
|
%1 = load i32, ptr %i, align 4, !tbaa !3
|
|
%2 = load i32, ptr %len.addr, align 4, !tbaa !3
|
|
%cmp1 = icmp slt i32 %1, %2
|
|
br i1 %cmp1, label %for.body, label %for.cond.cleanup
|
|
|
|
|
|
for.cond.cleanup: ; preds = %for.cond
|
|
call void @llvm.lifetime.end.p0(i64 4, ptr %i) #3
|
|
br label %for.end
|
|
|
|
for.body: ; preds = %for.cond
|
|
call void @llvm.lifetime.start.p0(i64 8, ptr %d) #3
|
|
%3 = load ptr, ptr %data.addr, align 8, !tbaa !7
|
|
%4 = load i8, ptr %3, align 1, !tbaa !9
|
|
%conv = sext i8 %4 to i32
|
|
%tobool = icmp ne i32 %conv, 0
|
|
br i1 %tobool, label %cond.true, label %cond.false
|
|
|
|
cond.true: ; preds = %for.body
|
|
br label %cond.end
|
|
|
|
cond.false: ; preds = %for.body
|
|
br label %cond.end
|
|
|
|
cond.end: ; preds = %cond.false, %cond.true
|
|
%cond = phi i32 [ %conv, %cond.true ], [ 48, %cond.false ]
|
|
%conv2 = sext i32 %cond to i64
|
|
store i64 %conv2, ptr %d, align 8, !tbaa !10
|
|
%5 = load i32, ptr %i, align 4, !tbaa !3
|
|
call void @foo(ptr @.str, i32 %5, ptr %d)
|
|
call void @llvm.lifetime.end.p0(i64 8, ptr %d) #3
|
|
br label %for.inc
|
|
|
|
for.inc: ; preds = %cond.end
|
|
%6 = load i32, ptr %i, align 4, !tbaa !3
|
|
%inc = add nsw i32 %6, 1
|
|
store i32 %inc, ptr %i, align 4, !tbaa !3
|
|
br label %for.cond, !llvm.loop !12
|
|
|
|
for.end: ; preds = %for.cond.cleanup
|
|
br label %if.end
|
|
|
|
if.end: ; preds = %for.end, %entry
|
|
ret i32 0
|
|
}
|
|
|
|
; Function Attrs: argmemonly nofree nosync nounwind willreturn
|
|
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1
|
|
|
|
declare dso_local void @foo(ptr, i32, ptr) #2
|
|
|
|
; Function Attrs: argmemonly nofree nosync nounwind willreturn
|
|
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1
|
|
|
|
attributes #0 = { nounwind "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
|
|
attributes #1 = { argmemonly nofree nosync nounwind willreturn }
|
|
attributes #2 = { "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
|
|
attributes #3 = { nounwind }
|
|
|
|
!llvm.module.flags = !{!0, !1}
|
|
!llvm.ident = !{!2}
|
|
|
|
!0 = !{i32 1, !"wchar_size", i32 4}
|
|
!1 = !{i32 7, !"frame-pointer", i32 2}
|
|
!2 = !{!"clang version 14.0.0 (https://github.com/llvm/llvm-project.git 8385de118443144518c9fba8b3d831d9076e746b)"}
|
|
!3 = !{!4, !4, i64 0}
|
|
!4 = !{!"int", !5, i64 0}
|
|
!5 = !{!"omnipotent char", !6, i64 0}
|
|
!6 = !{!"Simple C/C++ TBAA"}
|
|
!7 = !{!8, !8, i64 0}
|
|
!8 = !{!"any pointer", !5, i64 0}
|
|
!9 = !{!5, !5, i64 0}
|
|
!10 = !{!11, !11, i64 0}
|
|
!11 = !{!"long", !5, i64 0}
|
|
!12 = distinct !{!12, !13}
|
|
!13 = !{!"llvm.loop.mustprogress"}
|