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1; RUN: opt -O2 -S < %s | FileCheck %s2;3; This test tries to ensure that simplifycfg hoisting common instructions4; of then/else branch indeed happens. BPF target has added an IR pass5; before loop optimizations as Commit 1d51dc38d89b6; ([SimplifyCFG][LoopRotate] SimplifyCFG: disable common instruction7; hoisting by default, enable late in pipeline)8; disabled common instruction hoisting. Due to optimization triggered9; code changes, later SimplifyCFG may not be able to perform optimization10; even common inst hoisting is enabled.11;12; Source:13; typedef struct {14; void *f_back;15; } FrameData;16; extern int get_data(void *, void *);17; extern void get_frame_ptr(void *);18; int test() {19; void *frame_ptr;20; FrameData frame;21;22; get_frame_ptr(&frame_ptr);23;24; #pragma nounroll25; for (int i = 0; i < 6; i++) {26; if (frame_ptr && get_data(frame_ptr, &frame)) {27; frame_ptr = frame.f_back;28; }29; }30; return frame_ptr == 0;31; }32; Compilation flag:33; clang -target bpf -O2 -Xclang -disable-llvm-passes -S -emit-llvm t.c -o t.ll34 35target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128"36target triple = "bpf"37 38%struct.FrameData = type { ptr }39 40; Function Attrs: nounwind41define dso_local i32 @test() {42entry:43 %frame_ptr = alloca ptr, align 844 %frame = alloca %struct.FrameData, align 845 %i = alloca i32, align 446 call void @llvm.lifetime.start.p0(i64 8, ptr %frame_ptr)47 call void @llvm.lifetime.start.p0(i64 8, ptr %frame)48 call void @get_frame_ptr(ptr %frame_ptr)49 call void @llvm.lifetime.start.p0(i64 4, ptr %i)50 store i32 0, ptr %i, align 4, !tbaa !251 br label %for.cond52 53; CHECK-LABEL: entry54; CHECK: %[[PTR:[0-9]+]] = load ptr, ptr %frame_ptr, align 855; CHECK: %{{[0-9a-z.]+}} = icmp eq ptr %[[PTR]], null56; CHECK: br label57 58for.cond: ; preds = %for.inc, %entry59 %0 = load i32, ptr %i, align 4, !tbaa !260 %cmp = icmp slt i32 %0, 661 br i1 %cmp, label %for.body, label %for.cond.cleanup62 63for.cond.cleanup: ; preds = %for.cond64 call void @llvm.lifetime.end.p0(i64 4, ptr %i)65 br label %for.end66 67for.body: ; preds = %for.cond68 %1 = load ptr, ptr %frame_ptr, align 8, !tbaa !669 %tobool = icmp ne ptr %1, null70 br i1 %tobool, label %land.lhs.true, label %if.end71 72land.lhs.true: ; preds = %for.body73 %2 = load ptr, ptr %frame_ptr, align 8, !tbaa !674 %call = call i32 @get_data(ptr %2, ptr %frame)75 %tobool1 = icmp ne i32 %call, 076 br i1 %tobool1, label %if.then, label %if.end77 78if.then: ; preds = %land.lhs.true79 %3 = load ptr, ptr %frame, align 8, !tbaa !880 store ptr %3, ptr %frame_ptr, align 8, !tbaa !681 br label %if.end82 83if.end: ; preds = %if.then, %land.lhs.true, %for.body84 br label %for.inc85 86for.inc: ; preds = %if.end87 %4 = load i32, ptr %i, align 4, !tbaa !288 %inc = add nsw i32 %4, 189 store i32 %inc, ptr %i, align 4, !tbaa !290 br label %for.cond, !llvm.loop !1091 92for.end: ; preds = %for.cond.cleanup93 %5 = load ptr, ptr %frame_ptr, align 8, !tbaa !694 %cmp2 = icmp eq ptr %5, null95 %conv = zext i1 %cmp2 to i3296 call void @llvm.lifetime.end.p0(i64 8, ptr %frame)97 call void @llvm.lifetime.end.p0(i64 8, ptr %frame_ptr)98 ret i32 %conv99}100 101; Function Attrs: argmemonly nounwind willreturn102declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture)103 104declare dso_local void @get_frame_ptr(ptr)105 106declare dso_local i32 @get_data(ptr, ptr)107 108; Function Attrs: argmemonly nounwind willreturn109declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture)110 111!llvm.module.flags = !{!0}112!llvm.ident = !{!1}113 114!0 = !{i32 1, !"wchar_size", i32 4}115!1 = !{!"clang version 12.0.0 (https://github.com/llvm/llvm-project.git 1b3c1c543269da36ae41ab84f646cf98d2e5b1e5)"}116!2 = !{!3, !3, i64 0}117!3 = !{!"int", !4, i64 0}118!4 = !{!"omnipotent char", !5, i64 0}119!5 = !{!"Simple C/C++ TBAA"}120!6 = !{!7, !7, i64 0}121!7 = !{!"any pointer", !4, i64 0}122!8 = !{!9, !7, i64 0}123!9 = !{!"", !7, i64 0}124!10 = distinct !{!10, !11}125!11 = !{!"llvm.loop.unroll.disable"}126