X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=test%2FTransforms%2FCodeGenPrepare%2FX86%2Fselect.ll;fp=test%2FTransforms%2FCodeGenPrepare%2FX86%2Fselect.ll;h=5b1a0bafe0677e32cdbeb2d8a47631177ba6fe87;hb=62c113616ec77ceb2dca654d4a1cc288e1bb04fb;hp=0000000000000000000000000000000000000000;hpb=0b3441771844d9822234f9dbc570e45b6a748a11;p=oota-llvm.git

diff --git a/test/Transforms/CodeGenPrepare/X86/select.ll b/test/Transforms/CodeGenPrepare/X86/select.ll
new file mode 100644
index 00000000000..5b1a0bafe06
--- /dev/null
+++ b/test/Transforms/CodeGenPrepare/X86/select.ll
@@ -0,0 +1,114 @@
+; RUN: opt -codegenprepare -S < %s | FileCheck %s
+
+target triple = "x86_64-unknown-unknown"
+
+; Nothing to sink here, but this gets converted to a branch to
+; avoid stalling an out-of-order CPU on a predictable branch.
+
+define i32 @no_sink(double %a, double* %b, i32 %x, i32 %y)  {
+entry:
+  %load = load double, double* %b, align 8
+  %cmp = fcmp olt double %load, %a
+  %sel = select i1 %cmp, i32 %x, i32 %y
+  ret i32 %sel
+
+; CHECK-LABEL: @no_sink(
+; CHECK:    %load = load double, double* %b, align 8
+; CHECK:    %cmp = fcmp olt double %load, %a
+; CHECK:    br i1 %cmp, label %select.end, label %select.false
+; CHECK:  select.false:
+; CHECK:    br label %select.end
+; CHECK:  select.end:
+; CHECK:    %sel = phi i32 [ %x, %entry ], [ %y, %select.false ] 
+; CHECK:    ret i32 %sel
+}
+
+
+; An 'fdiv' is expensive, so sink it rather than speculatively execute it.
+
+define float @fdiv_true_sink(float %a, float %b) {
+entry:
+  %div = fdiv float %a, %b
+  %cmp = fcmp ogt float %a, 1.0
+  %sel = select i1 %cmp, float %div, float 2.0
+  ret float %sel
+
+; CHECK-LABEL: @fdiv_true_sink(
+; CHECK:    %cmp = fcmp ogt float %a, 1.0
+; CHECK:    br i1 %cmp, label %select.true.sink, label %select.end
+; CHECK:  select.true.sink:
+; CHECK:    %div = fdiv float %a, %b
+; CHECK:    br label %select.end
+; CHECK:  select.end:
+; CHECK:    %sel = phi float [ %div, %select.true.sink ], [ 2.000000e+00, %entry ]
+; CHECK:    ret float %sel
+}
+
+define float @fdiv_false_sink(float %a, float %b) {
+entry:
+  %div = fdiv float %a, %b
+  %cmp = fcmp ogt float %a, 3.0
+  %sel = select i1 %cmp, float 4.0, float %div
+  ret float %sel
+
+; CHECK-LABEL: @fdiv_false_sink(
+; CHECK:    %cmp = fcmp ogt float %a, 3.0
+; CHECK:    br i1 %cmp, label %select.end, label %select.false.sink
+; CHECK:  select.false.sink:
+; CHECK:    %div = fdiv float %a, %b
+; CHECK:    br label %select.end
+; CHECK:  select.end:
+; CHECK:    %sel = phi float [ 4.000000e+00, %entry ], [ %div, %select.false.sink ] 
+; CHECK:    ret float %sel
+}
+
+define float @fdiv_both_sink(float %a, float %b) {
+entry:
+  %div1 = fdiv float %a, %b
+  %div2 = fdiv float %b, %a
+  %cmp = fcmp ogt float %a, 5.0
+  %sel = select i1 %cmp, float %div1, float %div2
+  ret float %sel
+
+; CHECK-LABEL: @fdiv_both_sink(
+; CHECK:    %cmp = fcmp ogt float %a, 5.0
+; CHECK:    br i1 %cmp, label %select.true.sink, label %select.false.sink
+; CHECK:  select.true.sink:
+; CHECK:    %div1 = fdiv float %a, %b
+; CHECK:    br label %select.end
+; CHECK:  select.false.sink:
+; CHECK:    %div2 = fdiv float %b, %a
+; CHECK:    br label %select.end
+; CHECK:  select.end:
+; CHECK:    %sel = phi float [ %div1, %select.true.sink ], [ %div2, %select.false.sink ] 
+; CHECK:    ret float %sel
+}
+
+; An 'fadd' is not too expensive, so it's ok to speculate.
+
+define float @fadd_no_sink(float %a, float %b) {
+  %add = fadd float %a, %b
+  %cmp = fcmp ogt float 6.0, %a
+  %sel = select i1 %cmp, float %add, float 7.0 
+  ret float %sel
+
+; CHECK-LABEL: @fadd_no_sink(
+; CHECK:  %sel = select i1 %cmp, float %add, float 7.0 
+}
+
+; Possible enhancement: sinkability is only calculated with the direct
+; operand of the select, so we don't try to sink this. The fdiv cost is not
+; taken into account.
+
+define float @fdiv_no_sink(float %a, float %b) {
+entry:
+  %div = fdiv float %a, %b
+  %add = fadd float %div, %b
+  %cmp = fcmp ogt float %a, 1.0
+  %sel = select i1 %cmp, float %add, float 8.0
+  ret float %sel
+
+; CHECK-LABEL: @fdiv_no_sink(
+; CHECK:  %sel = select i1 %cmp, float %add, float 8.0 
+}
+