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llvm-mirror/test/Transforms/InstCombine/cast-select.ll
Sanjay Patel 665298049e [InstCombine] allow more narrowing of casted select
D47163 created a rule that we should not change the casted
type of a select when we have matching types in its compare condition.
That was intended to help vector codegen, but it also could create
situations where we miss subsequent folds as shown in PR44545:
https://bugs.llvm.org/show_bug.cgi?id=44545

By using shouldChangeType(), we can continue to get the vector folds
(because we always return false for vector types). But we also solve
the motivating bug because it's ok to narrow the scalar select in that
example.

Our canonicalization rules around select are a mess, but AFAICT, this
will not induce any infinite looping from the reverse transform (but
we'll need to watch for that possibility if committed).

Side note: there's a similar use of shouldChangeType() for phi ops
just below this diff, and the source and destination types appear to
be reversed.

Differential Revision: https://reviews.llvm.org/D72733
2020-01-27 16:35:50 -05:00

134 lines
5.0 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instcombine -S | FileCheck %s
define i64 @zext(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @zext(
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i32 0, i32 [[Z:%.*]]
; CHECK-NEXT: [[R:%.*]] = zext i32 [[SEL]] to i64
; CHECK-NEXT: ret i64 [[R]]
;
%cmp = icmp eq i32 %x, %y
%sel = select i1 %cmp, i32 0, i32 %z
%r = zext i32 %sel to i64
ret i64 %r
}
define <2 x i32> @zext_vec(<2 x i8> %x, <2 x i8> %y, <2 x i8> %z) {
; CHECK-LABEL: @zext_vec(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt <2 x i8> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[Z:%.*]], <2 x i8> <i8 42, i8 7>
; CHECK-NEXT: [[R:%.*]] = zext <2 x i8> [[SEL]] to <2 x i32>
; CHECK-NEXT: ret <2 x i32> [[R]]
;
%cmp = icmp ugt <2 x i8> %x, %y
%sel = select <2 x i1> %cmp, <2 x i8> %z, <2 x i8> <i8 42, i8 7>
%r = zext <2 x i8> %sel to <2 x i32>
ret <2 x i32> %r
}
define i64 @sext(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @sext(
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 42, i8 [[Z:%.*]]
; CHECK-NEXT: [[R:%.*]] = sext i8 [[SEL]] to i64
; CHECK-NEXT: ret i64 [[R]]
;
%cmp = icmp ult i8 %x, %y
%sel = select i1 %cmp, i8 42, i8 %z
%r = sext i8 %sel to i64
ret i64 %r
}
define <2 x i32> @sext_vec(<2 x i8> %x, <2 x i8> %y, <2 x i8> %z) {
; CHECK-LABEL: @sext_vec(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt <2 x i8> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[Z:%.*]], <2 x i8> <i8 42, i8 7>
; CHECK-NEXT: [[R:%.*]] = sext <2 x i8> [[SEL]] to <2 x i32>
; CHECK-NEXT: ret <2 x i32> [[R]]
;
%cmp = icmp ugt <2 x i8> %x, %y
%sel = select <2 x i1> %cmp, <2 x i8> %z, <2 x i8> <i8 42, i8 7>
%r = sext <2 x i8> %sel to <2 x i32>
ret <2 x i32> %r
}
define i16 @trunc(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @trunc(
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[TMP1:%.*]] = trunc i32 [[Z:%.*]] to i16
; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP]], i16 42, i16 [[TMP1]]
; CHECK-NEXT: ret i16 [[R]]
;
%cmp = icmp ult i32 %x, %y
%sel = select i1 %cmp, i32 42, i32 %z
%r = trunc i32 %sel to i16
ret i16 %r
}
define <2 x i32> @trunc_vec(<2 x i64> %x, <2 x i64> %y, <2 x i64> %z) {
; CHECK-LABEL: @trunc_vec(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt <2 x i64> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = select <2 x i1> [[CMP]], <2 x i64> [[Z:%.*]], <2 x i64> <i64 42, i64 7>
; CHECK-NEXT: [[R:%.*]] = trunc <2 x i64> [[SEL]] to <2 x i32>
; CHECK-NEXT: ret <2 x i32> [[R]]
;
%cmp = icmp ugt <2 x i64> %x, %y
%sel = select <2 x i1> %cmp, <2 x i64> %z, <2 x i64> <i64 42, i64 7>
%r = trunc <2 x i64> %sel to <2 x i32>
ret <2 x i32> %r
}
define double @fpext(float %x, float %y, float %z) {
; CHECK-LABEL: @fpext(
; CHECK-NEXT: [[CMP:%.*]] = fcmp oeq float [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], float 1.700000e+01, float [[Z:%.*]]
; CHECK-NEXT: [[R:%.*]] = fpext float [[SEL]] to double
; CHECK-NEXT: ret double [[R]]
;
%cmp = fcmp oeq float %x, %y
%sel = select i1 %cmp, float 17.0, float %z
%r = fpext float %sel to double
ret double %r
}
define <2 x double> @fpext_vec(<2 x float> %x, <2 x float> %y, <2 x float> %z) {
; CHECK-LABEL: @fpext_vec(
; CHECK-NEXT: [[CMP:%.*]] = fcmp ugt <2 x float> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = select <2 x i1> [[CMP]], <2 x float> [[Z:%.*]], <2 x float> <float 4.200000e+01, float -2.000000e+00>
; CHECK-NEXT: [[R:%.*]] = fpext <2 x float> [[SEL]] to <2 x double>
; CHECK-NEXT: ret <2 x double> [[R]]
;
%cmp = fcmp ugt <2 x float> %x, %y
%sel = select <2 x i1> %cmp, <2 x float> %z, <2 x float> <float 42.0, float -2.0>
%r = fpext <2 x float> %sel to <2 x double>
ret <2 x double> %r
}
define float @fptrunc(double %x, double %y, double %z) {
; CHECK-LABEL: @fptrunc(
; CHECK-NEXT: [[CMP:%.*]] = fcmp ult double [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], double 4.200000e+01, double [[Z:%.*]]
; CHECK-NEXT: [[R:%.*]] = fptrunc double [[SEL]] to float
; CHECK-NEXT: ret float [[R]]
;
%cmp = fcmp ult double %x, %y
%sel = select i1 %cmp, double 42.0, double %z
%r = fptrunc double %sel to float
ret float %r
}
define <2 x float> @fptrunc_vec(<2 x double> %x, <2 x double> %y, <2 x double> %z) {
; CHECK-LABEL: @fptrunc_vec(
; CHECK-NEXT: [[CMP:%.*]] = fcmp oge <2 x double> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = select <2 x i1> [[CMP]], <2 x double> [[Z:%.*]], <2 x double> <double -4.200000e+01, double 1.200000e+01>
; CHECK-NEXT: [[R:%.*]] = fptrunc <2 x double> [[SEL]] to <2 x float>
; CHECK-NEXT: ret <2 x float> [[R]]
;
%cmp = fcmp oge <2 x double> %x, %y
%sel = select <2 x i1> %cmp, <2 x double> %z, <2 x double> <double -42.0, double 12.0>
%r = fptrunc <2 x double> %sel to <2 x float>
ret <2 x float> %r
}