1; RUN: opt -codegenprepare -S < %s | FileCheck %s 2 3target triple = "x86_64-unknown-unknown" 4 5; Nothing to sink and convert here. 6 7define i32 @no_sink(double %a, double* %b, i32 %x, i32 %y) { 8entry: 9 %load = load double, double* %b, align 8 10 %cmp = fcmp olt double %load, %a 11 %sel = select i1 %cmp, i32 %x, i32 %y 12 ret i32 %sel 13 14; CHECK-LABEL: @no_sink( 15; CHECK: %load = load double, double* %b, align 8 16; CHECK: %cmp = fcmp olt double %load, %a 17; CHECK: %sel = select i1 %cmp, i32 %x, i32 %y 18; CHECK: ret i32 %sel 19} 20 21 22; An 'fdiv' is expensive, so sink it rather than speculatively execute it. 23 24define float @fdiv_true_sink(float %a, float %b) { 25entry: 26 %div = fdiv float %a, %b 27 %cmp = fcmp ogt float %a, 1.0 28 %sel = select i1 %cmp, float %div, float 2.0 29 ret float %sel 30 31; CHECK-LABEL: @fdiv_true_sink( 32; CHECK: %cmp = fcmp ogt float %a, 1.0 33; CHECK: br i1 %cmp, label %select.true.sink, label %select.end 34; CHECK: select.true.sink: 35; CHECK: %div = fdiv float %a, %b 36; CHECK: br label %select.end 37; CHECK: select.end: 38; CHECK: %sel = phi float [ %div, %select.true.sink ], [ 2.000000e+00, %entry ] 39; CHECK: ret float %sel 40} 41 42define float @fdiv_false_sink(float %a, float %b) { 43entry: 44 %div = fdiv float %a, %b 45 %cmp = fcmp ogt float %a, 3.0 46 %sel = select i1 %cmp, float 4.0, float %div 47 ret float %sel 48 49; CHECK-LABEL: @fdiv_false_sink( 50; CHECK: %cmp = fcmp ogt float %a, 3.0 51; CHECK: br i1 %cmp, label %select.end, label %select.false.sink 52; CHECK: select.false.sink: 53; CHECK: %div = fdiv float %a, %b 54; CHECK: br label %select.end 55; CHECK: select.end: 56; CHECK: %sel = phi float [ 4.000000e+00, %entry ], [ %div, %select.false.sink ] 57; CHECK: ret float %sel 58} 59 60define float @fdiv_both_sink(float %a, float %b) { 61entry: 62 %div1 = fdiv float %a, %b 63 %div2 = fdiv float %b, %a 64 %cmp = fcmp ogt float %a, 5.0 65 %sel = select i1 %cmp, float %div1, float %div2 66 ret float %sel 67 68; CHECK-LABEL: @fdiv_both_sink( 69; CHECK: %cmp = fcmp ogt float %a, 5.0 70; CHECK: br i1 %cmp, label %select.true.sink, label %select.false.sink 71; CHECK: select.true.sink: 72; CHECK: %div1 = fdiv float %a, %b 73; CHECK: br label %select.end 74; CHECK: select.false.sink: 75; CHECK: %div2 = fdiv float %b, %a 76; CHECK: br label %select.end 77; CHECK: select.end: 78; CHECK: %sel = phi float [ %div1, %select.true.sink ], [ %div2, %select.false.sink ] 79; CHECK: ret float %sel 80} 81 82; But if the select is marked unpredictable, then don't turn it into a branch. 83 84define float @unpredictable_select(float %a, float %b) { 85; CHECK-LABEL: @unpredictable_select( 86; CHECK-NEXT: entry: 87; CHECK-NEXT: [[DIV:%.*]] = fdiv float %a, %b 88; CHECK-NEXT: [[CMP:%.*]] = fcmp ogt float %a, 1.000000e+00 89; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], float [[DIV]], float 2.000000e+00, !unpredictable !0 90; CHECK-NEXT: ret float [[SEL]] 91; 92entry: 93 %div = fdiv float %a, %b 94 %cmp = fcmp ogt float %a, 1.0 95 %sel = select i1 %cmp, float %div, float 2.0, !unpredictable !0 96 ret float %sel 97} 98 99!0 = !{} 100 101; An 'fadd' is not too expensive, so it's ok to speculate. 102 103define float @fadd_no_sink(float %a, float %b) { 104 %add = fadd float %a, %b 105 %cmp = fcmp ogt float 6.0, %a 106 %sel = select i1 %cmp, float %add, float 7.0 107 ret float %sel 108 109; CHECK-LABEL: @fadd_no_sink( 110; CHECK: %sel = select i1 %cmp, float %add, float 7.0 111} 112 113; Possible enhancement: sinkability is only calculated with the direct 114; operand of the select, so we don't try to sink this. The fdiv cost is not 115; taken into account. 116 117define float @fdiv_no_sink(float %a, float %b) { 118entry: 119 %div = fdiv float %a, %b 120 %add = fadd float %div, %b 121 %cmp = fcmp ogt float %a, 1.0 122 %sel = select i1 %cmp, float %add, float 8.0 123 ret float %sel 124 125; CHECK-LABEL: @fdiv_no_sink( 126; CHECK: %sel = select i1 %cmp, float %add, float 8.0 127} 128 129; Do not transform the CFG if the select operands may have side effects. 130 131declare i64* @bar(i32, i32, i32) 132declare i64* @baz(i32, i32, i32) 133 134define i64* @calls_no_sink(i32 %in) { 135 %call1 = call i64* @bar(i32 1, i32 2, i32 3) 136 %call2 = call i64* @baz(i32 1, i32 2, i32 3) 137 %tobool = icmp ne i32 %in, 0 138 %sel = select i1 %tobool, i64* %call1, i64* %call2 139 ret i64* %sel 140 141; CHECK-LABEL: @calls_no_sink( 142; CHECK: %sel = select i1 %tobool, i64* %call1, i64* %call2 143} 144 145define i32 @sdiv_no_sink(i32 %a, i32 %b) { 146 %div1 = sdiv i32 %a, %b 147 %div2 = sdiv i32 %b, %a 148 %cmp = icmp sgt i32 %a, 5 149 %sel = select i1 %cmp, i32 %div1, i32 %div2 150 ret i32 %sel 151 152; CHECK-LABEL: @sdiv_no_sink( 153; CHECK: %sel = select i1 %cmp, i32 %div1, i32 %div2 154} 155 156