1; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/discriminator.prof | opt -analyze -branch-prob | FileCheck %s 2 3; Original code 4; 5; 1 int foo(int i) { 6; 2 int x = 0; 7; 3 while (i < 100) { 8; 4 if (i < 5) x--; 9; 5 i++; 10; 6 } 11; 7 return x; 12; 8 } 13; 14; In this test, if the loop is executed 100 times, the decrement operation 15; at line 4 should only execute 5 times. This is reflected in the profile 16; data for line offset 3. In Inputs/discriminator.prof, we have: 17; 18; 3: 100 19; 3.1: 5 20; 21; This means that the predicate 'i < 5' (line 3) is executed 100 times, 22; but the then branch (line 3.1) is only executed 5 times. 23 24define i32 @foo(i32 %i) #0 { 25; CHECK: Printing analysis 'Branch Probability Analysis' for function 'foo': 26entry: 27 %i.addr = alloca i32, align 4 28 %x = alloca i32, align 4 29 store i32 %i, i32* %i.addr, align 4 30 store i32 0, i32* %x, align 4, !dbg !10 31 br label %while.cond, !dbg !11 32 33while.cond: ; preds = %if.end, %entry 34 %0 = load i32* %i.addr, align 4, !dbg !12 35 %cmp = icmp slt i32 %0, 100, !dbg !12 36 br i1 %cmp, label %while.body, label %while.end, !dbg !12 37; CHECK: edge while.cond -> while.body probability is 100 / 101 = 99.0099% [HOT edge] 38; CHECK: edge while.cond -> while.end probability is 1 / 101 = 0.990099% 39 40while.body: ; preds = %while.cond 41 %1 = load i32* %i.addr, align 4, !dbg !14 42 %cmp1 = icmp slt i32 %1, 50, !dbg !14 43 br i1 %cmp1, label %if.then, label %if.end, !dbg !14 44; CHECK: edge while.body -> if.then probability is 5 / 100 = 5% 45; CHECK: edge while.body -> if.end probability is 95 / 100 = 95% [HOT edge] 46 47if.then: ; preds = %while.body 48 %2 = load i32* %x, align 4, !dbg !17 49 %dec = add nsw i32 %2, -1, !dbg !17 50 store i32 %dec, i32* %x, align 4, !dbg !17 51 br label %if.end, !dbg !17 52 53if.end: ; preds = %if.then, %while.body 54 %3 = load i32* %i.addr, align 4, !dbg !19 55 %inc = add nsw i32 %3, 1, !dbg !19 56 store i32 %inc, i32* %i.addr, align 4, !dbg !19 57 br label %while.cond, !dbg !20 58 59while.end: ; preds = %while.cond 60 %4 = load i32* %x, align 4, !dbg !21 61 ret i32 %4, !dbg !21 62} 63 64 65!llvm.dbg.cu = !{!0} 66!llvm.module.flags = !{!7, !8} 67!llvm.ident = !{!9} 68 69!0 = !{!"0x11\0012\00clang version 3.5 \000\00\000\00\000", !1, !2, !2, !3, !2, !2} ; [ DW_TAG_compile_unit ] [discriminator.c] [DW_LANG_C99] 70!1 = !{!"discriminator.c", !"."} 71!2 = !{} 72!3 = !{!4} 73!4 = !{!"0x2e\00foo\00foo\00\001\000\001\000\006\00256\000\001", !1, !5, !6, null, i32 (i32)* @foo, null, null, !2} ; [ DW_TAG_subprogram ] [line 1] [def] [foo] 74!5 = !{!"0x29", !1} ; [ DW_TAG_file_type ] [discriminator.c] 75!6 = !{!"0x15\00\000\000\000\000\000\000", i32 0, null, null, !2, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ] 76!7 = !{i32 2, !"Dwarf Version", i32 4} 77!8 = !{i32 1, !"Debug Info Version", i32 2} 78!9 = !{!"clang version 3.5 "} 79!10 = !MDLocation(line: 2, scope: !4) 80!11 = !MDLocation(line: 3, scope: !4) 81!12 = !MDLocation(line: 3, scope: !13) 82!13 = !{!"0xb\001", !1, !4} ; [ DW_TAG_lexical_block ] [discriminator.c] 83!14 = !MDLocation(line: 4, scope: !15) 84!15 = !{!"0xb\004\000\001", !1, !16} ; [ DW_TAG_lexical_block ] [discriminator.c] 85!16 = !{!"0xb\003\000\000", !1, !4} ; [ DW_TAG_lexical_block ] [discriminator.c] 86!17 = !MDLocation(line: 4, scope: !18) 87!18 = !{!"0xb\001", !1, !15} ; [ DW_TAG_lexical_block ] [discriminator.c] 88!19 = !MDLocation(line: 5, scope: !16) 89!20 = !MDLocation(line: 6, scope: !16) 90!21 = !MDLocation(line: 7, scope: !4) 91