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 24 define i32 @foo(i32 %i) #0 { 25 ; CHECK: Printing analysis 'Branch Probability Analysis' for function 'foo': 26 entry: 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 33 while.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 40 while.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 47 if.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 53 if.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 59 while.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 = metadata !{i32 786449, metadata !1, i32 12, metadata !"clang version 3.5 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [discriminator.c] [DW_LANG_C99] 70 !1 = metadata !{metadata !"discriminator.c", metadata !"."} 71 !2 = metadata !{} 72 !3 = metadata !{metadata !4} 73 !4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"foo", metadata !"foo", metadata !"", i32 1, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32)* @foo, null, null, metadata !2, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [foo] 74 !5 = metadata !{i32 786473, metadata !1} ; [ DW_TAG_file_type ] [discriminator.c] 75 !6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !2, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ] 76 !7 = metadata !{i32 2, metadata !"Dwarf Version", i32 4} 77 !8 = metadata !{i32 1, metadata !"Debug Info Version", i32 1} 78 !9 = metadata !{metadata !"clang version 3.5 "} 79 !10 = metadata !{i32 2, i32 0, metadata !4, null} 80 !11 = metadata !{i32 3, i32 0, metadata !4, null} 81 !12 = metadata !{i32 3, i32 0, metadata !13, null} 82 !13 = metadata !{i32 786443, metadata !1, metadata !4, i32 3, i32 0, i32 1, i32 2} ; [ DW_TAG_lexical_block ] [discriminator.c] 83 !14 = metadata !{i32 4, i32 0, metadata !15, null} 84 !15 = metadata !{i32 786443, metadata !1, metadata !16, i32 4, i32 0, i32 0, i32 1} ; [ DW_TAG_lexical_block ] [discriminator.c] 85 !16 = metadata !{i32 786443, metadata !1, metadata !4, i32 3, i32 0, i32 0, i32 0} ; [ DW_TAG_lexical_block ] [discriminator.c] 86 !17 = metadata !{i32 4, i32 0, metadata !18, null} 87 !18 = metadata !{i32 786443, metadata !1, metadata !15, i32 4, i32 0, i32 1, i32 3} ; [ DW_TAG_lexical_block ] [discriminator.c] 88 !19 = metadata !{i32 5, i32 0, metadata !16, null} 89 !20 = metadata !{i32 6, i32 0, metadata !16, null} 90 !21 = metadata !{i32 7, i32 0, metadata !4, null} 91
