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[InstCombine] add tests for another abs() pattern (PR36036); NFC 

llvm-svn: 334133
This commit is contained in:
Sanjay Patel 2018-06-06 21:32:42 +00:00
parent e9524f1fb3
commit 6fda6b1210
1 changed files with 56 additions and 0 deletions
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56
llvm/test/Transforms/InstCombine/abs-1.ll
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@ -296,6 +296,61 @@ define i8 @shifty_abs_too_many_uses(i8 %x) {
ret i8 %abs
}
; There's another way to make abs() using shift, xor, and subtract.
; PR36036 - https://bugs.llvm.org/show_bug.cgi?id=36036
define i8 @shifty_sub(i8 %x) {
; CHECK-LABEL: @shifty_sub(
; CHECK-NEXT: [[SH:%.*]] = ashr i8 [[X:%.*]], 7
; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[SH]], [[X]]
; CHECK-NEXT: [[R:%.*]] = sub i8 [[XOR]], [[SH]]
; CHECK-NEXT: ret i8 [[R]]
;
%sh = ashr i8 %x, 7
%xor = xor i8 %x, %sh
%r = sub i8 %xor, %sh
ret i8 %r
}
define i8 @shifty_sub_nsw_commute(i8 %x) {
; CHECK-LABEL: @shifty_sub_nsw_commute(
; CHECK-NEXT: [[SH:%.*]] = ashr i8 [[X:%.*]], 7
; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[SH]], [[X]]
; CHECK-NEXT: [[R:%.*]] = sub nsw i8 [[XOR]], [[SH]]
; CHECK-NEXT: ret i8 [[R]]
;
%sh = ashr i8 %x, 7
%xor = xor i8 %sh, %x
%r = sub nsw i8 %xor, %sh
ret i8 %r
}
define <4 x i32> @shifty_sub_nuw_vec_commute(<4 x i32> %x) {
; CHECK-LABEL: @shifty_sub_nuw_vec_commute(
; CHECK-NEXT: [[SH:%.*]] = ashr <4 x i32> [[X:%.*]], <i32 31, i32 31, i32 31, i32 31>
; CHECK-NEXT: [[XOR:%.*]] = xor <4 x i32> [[SH]], [[X]]
; CHECK-NEXT: [[R:%.*]] = sub nuw <4 x i32> [[XOR]], [[SH]]
; CHECK-NEXT: ret <4 x i32> [[R]]
;
%sh = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31>
%xor = xor <4 x i32> %sh, %x
%r = sub nuw <4 x i32> %xor, %sh
ret <4 x i32> %r
}
define i12 @shifty_sub_nsw_nuw(i12 %x) {
; CHECK-LABEL: @shifty_sub_nsw_nuw(
; CHECK-NEXT: [[SH:%.*]] = ashr i12 [[X:%.*]], 11
; CHECK-NEXT: [[XOR:%.*]] = xor i12 [[SH]], [[X]]
; CHECK-NEXT: [[R:%.*]] = sub nuw nsw i12 [[XOR]], [[SH]]
; CHECK-NEXT: ret i12 [[R]]
;
%sh = ashr i12 %x, 11
%xor = xor i12 %x, %sh
%r = sub nsw nuw i12 %xor, %sh
ret i12 %r
}
define i8 @negate_abs(i8 %x) {
; CHECK-LABEL: @negate_abs(
; CHECK-NEXT: [[N:%.*]] = sub i8 0, [[X:%.*]]
@ -334,3 +389,4 @@ define i1 @abs_must_be_positive(i32 %x) {
%c2 = icmp sge i32 %sel, 0
ret i1 %c2
}