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llvm-mirror/test/Transforms/InstCombine/vector-logical-reductions.ll
Alexey Bataev 8ef51c94ae [Instcombiner]Improve emission of logical or/and reductions.
For logical or/and reductions we emit regular intrinsics @llvm.vector.reduce.or/and.vxi1 calls.
These intrinsics are not effective for the logical or/and reductions,
especially if the optimizer is able to emit short circuit versions of
the scalar or/and instructions and vector code gets less effective than
the scalar version.
Instead, or reduction for i1 can be represented as:
```
%val = bitcast <ReduxWidth x i1> to iReduxWidth
%res = cmp ne iReduxWidth %val, 0
```
and reduction for i1 can be represented as:
```
%val = bitcast <ReduxWidth x i1> to iReduxWidth
%res = cmp eq iReduxWidth %val, 11111
```
This improves perfromance of the vector code significantly and make it
to outperform short circuit scalar code.

Part of D57059.

Differential Revision: https://reviews.llvm.org/D97406
2021-03-04 08:01:02 -08:00

26 lines
847 B
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instcombine -S | FileCheck %s
define i1 @reduction_logical_or(<4 x i1> %x) {
; CHECK-LABEL: @reduction_logical_or(
; CHECK-NEXT: [[TMP1:%.*]] = bitcast <4 x i1> [[X:%.*]] to i4
; CHECK-NEXT: [[TMP2:%.*]] = icmp ne i4 [[TMP1]], 0
; CHECK-NEXT: ret i1 [[TMP2]]
;
%r = call i1 @llvm.vector.reduce.or.v4i1(<4 x i1> %x)
ret i1 %r
}
define i1 @reduction_logical_and(<4 x i1> %x) {
; CHECK-LABEL: @reduction_logical_and(
; CHECK-NEXT: [[TMP1:%.*]] = bitcast <4 x i1> [[X:%.*]] to i4
; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i4 [[TMP1]], -1
; CHECK-NEXT: ret i1 [[TMP2]]
;
%r = call i1 @llvm.vector.reduce.and.v4i1(<4 x i1> %x)
ret i1 %r
}
declare i1 @llvm.vector.reduce.or.v4i1(<4 x i1>)
declare i1 @llvm.vector.reduce.and.v4i1(<4 x i1>)