[test cases] add test cases for find more abs pattern

[shchenz]

Summary

two more abs pattern and canonicalize abs pattern, this is for D48754
1:

define i32 @abs_canonical_6(i32 %a, i32 %b) {
  %tmp1 = sub i32 %a, %b
  %cmp = icmp sgt i32 %tmp1, -1
  %tmp2 = sub i32 %b, %a
  %abs = select i1 %cmp, i32 %tmp1, i32 %tmp2
  ret i32 %abs
}

this should be |a-b|.

2:

define <2 x i8> @abs_canonical_7(<2 x i8> %a, <2 x i8 > %b) {
  %tmp1 = sub <2 x i8> %a, %b
  %cmp = icmp sgt <2 x i8> %tmp1, <i8 -1, i8 -1>
  %tmp2 = sub <2 x i8> %b, %a
  %abs = select <2 x i1> %cmp, <2 x i8> %tmp1, <2 x i8> %tmp2
  ret <2 x i8> %abs
}

this should be |a-b| for vector type

3:

define i32 @abs_canonical_8(i32 %a) {
; CHECK-LABEL: @abs_canonical_8(
; CHECK-NEXT:    [[TMP:%.*]] = sub i32 0, [[A:%.*]]
; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[TMP]], 0
; CHECK-NEXT:    [[ABS:%.*]] = select i1 [[CMP]], i32 [[A]], i32 [[TMP]]
; CHECK-NEXT:    ret i32 [[ABS]]
;
  %tmp = sub i32 0, %a
  %cmp = icmp slt i32 %tmp, 0
  %abs = select i1 %cmp, i32 %a, i32 %tmp
  ret i32 %abs
}

this should be |-a| -> |a|

Also add test cases for -|a-b|(i32 and vector), -|-a|(-|a|)

[spatel]

The summary text description doesn't match the tests that are being added. The 'sgt -1' cases already exist as "@abs_canonical_2" and @nabs_canonical_2"?

llvm/test/Transforms/InstCombine/abs-1.ll

149

This is just verifying that the code does not change?

[shchenz]

@spatel Hi Sanjay, thanks very much for your comment. I have updated the description. For duplicated test case issue, "@abs_canonical_2" and @nabs_canonical_2" is for |x|, but my three case is for |-a|, |a-b| for int and vector. I am not clear you mean which one is duplicated?

llvm/test/Transforms/InstCombine/abs-1.ll

149

This case is for later abs pattern finding in D48754. with current master branch, there is no change to this code. I can surely add some other pred like sle to icmp to test some canonicalization for icmp. But I think this is not this test's purpose, so I let it unchanged. Should every case need changed even it is a baseline for later patch?

[spatel]

In D49123#1157270, @shchenz wrote:

@spatel Hi Sanjay, thanks very much for your comment. I have updated the description. For duplicated test case issue, "@abs_canonical_2" and @nabs_canonical_2" is for |x|, but my three case is for |-a|, |a-b| for int and vector. I am not clear you mean which one is duplicated?

Ah, I missed that the icmp in abs_canonical_8() is with the negated value. LGTM.

[spatel]

This patch was committed, but Phab did not recognize the formatting in the commit message (leading spaces on each line?), so it didn't close this review:
rL336752

[shchenz]

@spatel , thanks Sanjay for closing this item. Yes, I add two spaces in front of every line manually. I think there should be no need to do that.

llvm/test/Transforms/InstCombine/abs-1.ll

 ;
   %cmp = icmp sgt i8 %x, 0
   %conv = sext i8 %x to i32
   %neg = sub i32 0, %conv
   %abs = select i1 %cmp, i32 %conv, i32 %neg
   ret i32 %abs
 }
 
+define i32 @abs_canonical_6(i32 %a, i32 %b) {
+; CHECK-LABEL: @abs_canonical_6(
+; CHECK-NEXT:    [[TMP1:%.*]] = sub i32 [[A:%.*]], [[B:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[TMP1]], -1
+; CHECK-NEXT:    [[TMP2:%.*]] = sub i32 [[B]], [[A]]
+; CHECK-NEXT:    [[ABS:%.*]] = select i1 [[CMP]], i32 [[TMP1]], i32 [[TMP2]]
+; CHECK-NEXT:    ret i32 [[ABS]]
+;
+  %tmp1 = sub i32 %a, %b
+  %cmp = icmp sgt i32 %tmp1, -1
+  %tmp2 = sub i32 %b, %a
+  %abs = select i1 %cmp, i32 %tmp1, i32 %tmp2
+  ret i32 %abs
+}
+
+define <2 x i8> @abs_canonical_7(<2 x i8> %a, <2 x i8 > %b) {
+; CHECK-LABEL: @abs_canonical_7(
+; CHECK-NEXT:    [[TMP1:%.*]] = sub <2 x i8> [[A:%.*]], [[B:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i8> [[TMP1]], <i8 -1, i8 -1>
+; CHECK-NEXT:    [[TMP2:%.*]] = sub <2 x i8> [[B]], [[A]]
+; CHECK-NEXT:    [[ABS:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[TMP1]], <2 x i8> [[TMP2]]
+; CHECK-NEXT:    ret <2 x i8> [[ABS]]
+;
+  %tmp1 = sub <2 x i8> %a, %b
+  %cmp = icmp sgt <2 x i8> %tmp1, <i8 -1, i8 -1>
+  %tmp2 = sub <2 x i8> %b, %a
+  %abs = select <2 x i1> %cmp, <2 x i8> %tmp1, <2 x i8> %tmp2
+  ret <2 x i8> %abs
+}
+
+define i32 @abs_canonical_8(i32 %a) {
+; CHECK-LABEL: @abs_canonical_8(
+; CHECK-NEXT:    [[TMP:%.*]] = sub i32 0, [[A:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[TMP]], 0
+; CHECK-NEXT:    [[ABS:%.*]] = select i1 [[CMP]], i32 [[A]], i32 [[TMP]]
+; CHECK-NEXT:    ret i32 [[ABS]]
+;
+  %tmp = sub i32 0, %a
+  %cmp = icmp slt i32 %tmp, 0
+  %abs = select i1 %cmp, i32 %a, i32 %tmp
+  ret i32 %abs
+}
+
 ; We have a canonical form of nabs to make CSE easier.
 
 define i8 @nabs_canonical_1(i8 %x) {
 ; CHECK-LABEL: @nabs_canonical_1(
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0
 ; CHECK-NEXT:    [[NEG:%.*]] = sub i8 0, [[X]]
 ; CHECK-NEXT:    [[ABS:%.*]] = select i1 [[CMP]], i8 [[X]], i8 [[NEG]]
 ; CHECK-NEXT:    ret i8 [[ABS]]

 ;
   %cmp = icmp sgt i8 %x, 0
   %conv = sext i8 %x to i32
   %neg = sub i32 0, %conv
   %abs = select i1 %cmp, i32 %neg, i32 %conv
   ret i32 %abs
 }
 
+define i32 @nabs_canonical_6(i32 %a, i32 %b) {
+; CHECK-LABEL: @nabs_canonical_6(
+; CHECK-NEXT:    [[TMP1:%.*]] = sub i32 [[A:%.*]], [[B:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[TMP1]], -1
+; CHECK-NEXT:    [[TMP2:%.*]] = sub i32 [[B]], [[A]]
+; CHECK-NEXT:    [[ABS:%.*]] = select i1 [[CMP]], i32 [[TMP2]], i32 [[TMP1]]
+; CHECK-NEXT:    ret i32 [[ABS]]
+;
+  %tmp1 = sub i32 %a, %b
+  %cmp = icmp sgt i32 %tmp1, -1
+  %tmp2 = sub i32 %b, %a
+  %abs = select i1 %cmp, i32 %tmp2, i32 %tmp1
+  ret i32 %abs
+}
+
+define <2 x i8> @nabs_canonical_7(<2 x i8> %a, <2 x i8 > %b) {
+; CHECK-LABEL: @nabs_canonical_7(
+; CHECK-NEXT:    [[TMP1:%.*]] = sub <2 x i8> [[A:%.*]], [[B:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i8> [[TMP1]], <i8 -1, i8 -1>
+; CHECK-NEXT:    [[TMP2:%.*]] = sub <2 x i8> [[B]], [[A]]
+; CHECK-NEXT:    [[ABS:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[TMP2]], <2 x i8> [[TMP1]]
+; CHECK-NEXT:    ret <2 x i8> [[ABS]]
+;
+  %tmp1 = sub <2 x i8> %a, %b
+  %cmp = icmp sgt <2 x i8> %tmp1, <i8 -1, i8 -1>
+  %tmp2 = sub <2 x i8> %b, %a
+  %abs = select <2 x i1> %cmp, <2 x i8> %tmp2, <2 x i8> %tmp1
+  ret <2 x i8> %abs
+}
+
+define i32 @nabs_canonical_8(i32 %a) {
+; CHECK-LABEL: @nabs_canonical_8(
+; CHECK-NEXT:    [[TMP:%.*]] = sub i32 0, [[A:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[TMP]], 0
+; CHECK-NEXT:    [[ABS:%.*]] = select i1 [[CMP]], i32 [[TMP]], i32 [[A]]
+; CHECK-NEXT:    ret i32 [[ABS]]
+;
+  %tmp = sub i32 0, %a
+  %cmp = icmp slt i32 %tmp, 0
+  %abs = select i1 %cmp, i32 %tmp, i32 %a
+  ret i32 %abs
+}
+
 ; The following 5 tests use a shift+add+xor to implement abs():
 ; B = ashr i8 A, 7  -- smear the sign bit.
 ; xor (add A, B), B -- add -1 and flip bits if negative
 
 define i8 @shifty_abs_commute0(i8 %x) {
 ; CHECK-LABEL: @shifty_abs_commute0(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt i8 [[X:%.*]], 0
 ; CHECK-NEXT:    [[TMP2:%.*]] = sub i8 0, [[X]]