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[InstSimplify] Add test cases for opportunities to fold select ?, X, undef -> X when we can prove X isn't poison

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Part of addressing post-commit feedback from D83360
This commit is contained in:
Craig Topper
2020-07-08 15:19:49 -07:00
parent 3728133d3f
commit ac0af12ed2
1 changed files with 58 additions and 0 deletions
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58
llvm/test/Transforms/InstSimplify/select.ll
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@@ -790,3 +790,61 @@ define <2 x i32> @true_undef_vec(i1 %cond, <2 x i32> %x) {
%s = select i1 %cond, <2 x i32> undef, <2 x i32> %x
ret <2 x i32> %s
}
; These can be folded because the other value is guaranteed not to be poison.
define i32 @false_undef_true_constant(i1 %cond) {
; CHECK-LABEL: @false_undef_true_constant(
; CHECK-NEXT: [[S:%.*]] = select i1 [[COND:%.*]], i32 10, i32 undef
; CHECK-NEXT: ret i32 [[S]]
;
%s = select i1 %cond, i32 10, i32 undef
ret i32 %s
}
define i32 @true_undef_false_constant(i1 %cond) {
; CHECK-LABEL: @true_undef_false_constant(
; CHECK-NEXT: [[S:%.*]] = select i1 [[COND:%.*]], i32 undef, i32 20
; CHECK-NEXT: ret i32 [[S]]
;
%s = select i1 %cond, i32 undef, i32 20
ret i32 %s
}
define <2 x i32> @false_undef_true_constant_vec(i1 %cond) {
; CHECK-LABEL: @false_undef_true_constant_vec(
; CHECK-NEXT: ret <2 x i32> <i32 42, i32 -42>
;
%s = select i1 %cond, <2 x i32> <i32 42, i32 -42>, <2 x i32> undef
ret <2 x i32> %s
}
define <2 x i32> @true_undef_false_constant_vec(i1 %cond) {
; CHECK-LABEL: @true_undef_false_constant_vec(
; CHECK-NEXT: ret <2 x i32> <i32 -42, i32 42>
;
%s = select i1 %cond, <2 x i32> undef, <2 x i32> <i32 -42, i32 42>
ret <2 x i32> %s
}
; If one input is undef and the other is freeze, we can fold it to the freeze.
define i32 @false_undef_true_freeze(i1 %cond, i32 %x) {
; CHECK-LABEL: @false_undef_true_freeze(
; CHECK-NEXT: [[XF:%.*]] = freeze i32 [[X:%.*]]
; CHECK-NEXT: [[S:%.*]] = select i1 [[COND:%.*]], i32 [[XF]], i32 undef
; CHECK-NEXT: ret i32 [[S]]
;
%xf = freeze i32 %x
%s = select i1 %cond, i32 %xf, i32 undef
ret i32 %s
}
define i32 @false_undef_false_freeze(i1 %cond, i32 %x) {
; CHECK-LABEL: @false_undef_false_freeze(
; CHECK-NEXT: [[XF:%.*]] = freeze i32 [[X:%.*]]
; CHECK-NEXT: [[S:%.*]] = select i1 [[COND:%.*]], i32 undef, i32 [[XF]]
; CHECK-NEXT: ret i32 [[S]]
;
%xf = freeze i32 %x
%s = select i1 %cond, i32 undef, i32 %xf
ret i32 %s
}