1; RUN: opt -O2 -S < %s | FileCheck %s 2; 3; This test tries to ensure that simplifycfg hoisting common instructions 4; of then/else branch indeed happens. BPF target has added an IR pass 5; before loop optimizations as Commit 1d51dc38d89b 6; ([SimplifyCFG][LoopRotate] SimplifyCFG: disable common instruction 7; hoisting by default, enable late in pipeline) 8; disabled common instruction hoisting. Due to optimization triggered 9; code changes, later SimplifyCFG may not be able to perform optimization 10; 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 nounroll 25; 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.ll 34 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: nounwind 41define dso_local i32 @test() #0 { 42entry: 43 %frame_ptr = alloca ptr, align 8 44 %frame = alloca %struct.FrameData, align 8 45 %i = alloca i32, align 4 46 call void @llvm.lifetime.start.p0(i64 8, ptr %frame_ptr) #3 47 call void @llvm.lifetime.start.p0(i64 8, ptr %frame) #3 48 call void @get_frame_ptr(ptr %frame_ptr) 49 call void @llvm.lifetime.start.p0(i64 4, ptr %i) #3 50 store i32 0, ptr %i, align 4, !tbaa !2 51 br label %for.cond 52 53; CHECK-LABEL: entry 54; CHECK: %[[PTR:[0-9]+]] = load ptr, ptr %frame_ptr, align 8 55; CHECK: %{{[0-9a-z.]+}} = icmp eq ptr %[[PTR]], null 56; CHECK: br label 57 58for.cond: ; preds = %for.inc, %entry 59 %0 = load i32, ptr %i, align 4, !tbaa !2 60 %cmp = icmp slt i32 %0, 6 61 br i1 %cmp, label %for.body, label %for.cond.cleanup 62 63for.cond.cleanup: ; preds = %for.cond 64 call void @llvm.lifetime.end.p0(i64 4, ptr %i) #3 65 br label %for.end 66 67for.body: ; preds = %for.cond 68 %1 = load ptr, ptr %frame_ptr, align 8, !tbaa !6 69 %tobool = icmp ne ptr %1, null 70 br i1 %tobool, label %land.lhs.true, label %if.end 71 72land.lhs.true: ; preds = %for.body 73 %2 = load ptr, ptr %frame_ptr, align 8, !tbaa !6 74 %call = call i32 @get_data(ptr %2, ptr %frame) 75 %tobool1 = icmp ne i32 %call, 0 76 br i1 %tobool1, label %if.then, label %if.end 77 78if.then: ; preds = %land.lhs.true 79 %3 = load ptr, ptr %frame, align 8, !tbaa !8 80 store ptr %3, ptr %frame_ptr, align 8, !tbaa !6 81 br label %if.end 82 83if.end: ; preds = %if.then, %land.lhs.true, %for.body 84 br label %for.inc 85 86for.inc: ; preds = %if.end 87 %4 = load i32, ptr %i, align 4, !tbaa !2 88 %inc = add nsw i32 %4, 1 89 store i32 %inc, ptr %i, align 4, !tbaa !2 90 br label %for.cond, !llvm.loop !10 91 92for.end: ; preds = %for.cond.cleanup 93 %5 = load ptr, ptr %frame_ptr, align 8, !tbaa !6 94 %cmp2 = icmp eq ptr %5, null 95 %conv = zext i1 %cmp2 to i32 96 call void @llvm.lifetime.end.p0(i64 8, ptr %frame) #3 97 call void @llvm.lifetime.end.p0(i64 8, ptr %frame_ptr) #3 98 ret i32 %conv 99} 100 101; Function Attrs: argmemonly nounwind willreturn 102declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1 103 104declare dso_local void @get_frame_ptr(ptr) #2 105 106declare dso_local i32 @get_data(ptr, ptr) #2 107 108; Function Attrs: argmemonly nounwind willreturn 109declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1 110 111attributes #0 = { nounwind "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"="true" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } 112attributes #1 = { argmemonly nounwind willreturn } 113attributes #2 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } 114attributes #3 = { nounwind } 115 116!llvm.module.flags = !{!0} 117!llvm.ident = !{!1} 118 119!0 = !{i32 1, !"wchar_size", i32 4} 120!1 = !{!"clang version 12.0.0 (https://github.com/llvm/llvm-project.git 1b3c1c543269da36ae41ab84f646cf98d2e5b1e5)"} 121!2 = !{!3, !3, i64 0} 122!3 = !{!"int", !4, i64 0} 123!4 = !{!"omnipotent char", !5, i64 0} 124!5 = !{!"Simple C/C++ TBAA"} 125!6 = !{!7, !7, i64 0} 126!7 = !{!"any pointer", !4, i64 0} 127!8 = !{!9, !7, i64 0} 128!9 = !{!"", !7, i64 0} 129!10 = distinct !{!10, !11} 130!11 = !{!"llvm.loop.unroll.disable"} 131