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