[AArch64] Match ZIP and UZP starting from undef elements. #89578
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
In case the first element of a zip/uzp mask is undef, the isZIPMask and isUZPMask functions have a 50% chance of picking the wrong "WhichResult", meaning they don't match a zip/uzp where they could. This patch alters the matching code to first check for the first non-undef element, to try and get WhichResult correct.
davemgreen
requested review from
SamTebbs33,
jaykang10,
labrinea and
sjoerdmeijer
Member
|
@llvm/pr-subscribers-backend-aarch64 Author: David Green (davemgreen) ChangesIn case the first element of a zip/uzp mask is undef, the isZIPMask and isUZPMask functions have a 50% chance of picking the wrong "WhichResult", meaning they don't match a zip/uzp where they could. This patch alters the matching code to first check for the first non-undef element, to try and get WhichResult correct. Full diff: https://github.com/llvm/llvm-project/pull/89578.diff 3 Files Affected:
diff --git a/llvm/lib/Target/AArch64/AArch64PerfectShuffle.h b/llvm/lib/Target/AArch64/AArch64PerfectShuffle.h
index 7abaead694d114..a143243a8d3bb3 100644
--- a/llvm/lib/Target/AArch64/AArch64PerfectShuffle.h
+++ b/llvm/lib/Target/AArch64/AArch64PerfectShuffle.h
@@ -6620,11 +6620,28 @@ static unsigned getPerfectShuffleCost(llvm::ArrayRef<int> M) {
return (PFEntry >> 30) + 1;
}
-inline bool isZIPMask(ArrayRef<int> M, EVT VT, unsigned &WhichResult) {
+/// Return true for zip1 or zip2 masks of the form:
+/// <0, 8, 1, 9, 2, 10, 3, 11> or
+/// <4, 12, 5, 13, 6, 14, 7, 15>
+inline bool isZIPMask(ArrayRef<int> M, EVT VT, unsigned &WhichResultOut) {
unsigned NumElts = VT.getVectorNumElements();
if (NumElts % 2 != 0)
return false;
- WhichResult = (M[0] == 0 ? 0 : 1);
+ // Check the first non-undef element for which half to use.
+ unsigned WhichResult = 2;
+ for (unsigned i = 0; i != NumElts / 2; i++) {
+ if (M[i * 2] >= 0) {
+ WhichResult = ((unsigned)M[i * 2] == i ? 0 : 1);
+ break;
+ } else if (M[i * 2 + 1] >= 0) {
+ WhichResult = ((unsigned)M[i * 2 + 1] == NumElts + i ? 0 : 1);
+ break;
+ }
+ }
+ if (WhichResult == 2)
+ return false;
+
+ // Check all elements match.
unsigned Idx = WhichResult * NumElts / 2;
for (unsigned i = 0; i != NumElts; i += 2) {
if ((M[i] >= 0 && (unsigned)M[i] != Idx) ||
@@ -6632,20 +6649,34 @@ inline bool isZIPMask(ArrayRef<int> M, EVT VT, unsigned &WhichResult) {
return false;
Idx += 1;
}
-
+ WhichResultOut = WhichResult;
return true;
}
-inline bool isUZPMask(ArrayRef<int> M, EVT VT, unsigned &WhichResult) {
+/// Return true for uzp1 or uzp2 masks of the form:
+/// <0, 2, 4, 6, 8, 10, 12, 14> or
+/// <1, 3, 5, 7, 9, 11, 13, 15>
+inline bool isUZPMask(ArrayRef<int> M, EVT VT, unsigned &WhichResultOut) {
unsigned NumElts = VT.getVectorNumElements();
- WhichResult = (M[0] == 0 ? 0 : 1);
+ // Check the first non-undef element for which half to use.
+ unsigned WhichResult = 2;
+ for (unsigned i = 0; i != NumElts; i++) {
+ if (M[i] >= 0) {
+ WhichResult = ((unsigned)M[i] == i * 2 ? 0 : 1);
+ break;
+ }
+ }
+ if (WhichResult == 2)
+ return false;
+
+ // Check all elements match.
for (unsigned i = 0; i != NumElts; ++i) {
if (M[i] < 0)
continue; // ignore UNDEF indices
if ((unsigned)M[i] != 2 * i + WhichResult)
return false;
}
-
+ WhichResultOut = WhichResult;
return true;
}
diff --git a/llvm/test/CodeGen/AArch64/arm64-uzp.ll b/llvm/test/CodeGen/AArch64/arm64-uzp.ll
index 6e01ebc95a1cb8..49a51d96fbc841 100644
--- a/llvm/test/CodeGen/AArch64/arm64-uzp.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-uzp.ll
@@ -110,13 +110,9 @@ define <8 x i16> @vuzpQi16_undef1(<8 x i16> %A, <8 x i16> %B) nounwind {
define <8 x i16> @vuzpQi16_undef0(<8 x i16> %A, <8 x i16> %B) nounwind {
; CHECK-LABEL: vuzpQi16_undef0:
; CHECK: // %bb.0:
-; CHECK-NEXT: adrp x8, .LCPI8_0
-; CHECK-NEXT: // kill: def $q1 killed $q1 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: ldr q2, [x8, :lo12:.LCPI8_0]
-; CHECK-NEXT: // kill: def $q0 killed $q0 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: uzp2.8h v3, v0, v1
-; CHECK-NEXT: tbl.16b v0, { v0, v1 }, v2
-; CHECK-NEXT: add.8h v0, v0, v3
+; CHECK-NEXT: uzp1.8h v2, v0, v1
+; CHECK-NEXT: uzp2.8h v0, v0, v1
+; CHECK-NEXT: add.8h v0, v2, v0
; CHECK-NEXT: ret
%tmp3 = shufflevector <8 x i16> %A, <8 x i16> %B, <8 x i32> <i32 undef, i32 2, i32 4, i32 6, i32 8, i32 10, i32 12, i32 14>
%tmp4 = shufflevector <8 x i16> %A, <8 x i16> %B, <8 x i32> <i32 undef, i32 3, i32 5, i32 7, i32 9, i32 11, i32 13, i32 15>
@@ -127,13 +123,9 @@ define <8 x i16> @vuzpQi16_undef0(<8 x i16> %A, <8 x i16> %B) nounwind {
define <8 x i16> @vuzpQi16_undef01(<8 x i16> %A, <8 x i16> %B) nounwind {
; CHECK-LABEL: vuzpQi16_undef01:
; CHECK: // %bb.0:
-; CHECK-NEXT: adrp x8, .LCPI9_0
-; CHECK-NEXT: // kill: def $q1 killed $q1 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: ldr q2, [x8, :lo12:.LCPI9_0]
-; CHECK-NEXT: // kill: def $q0 killed $q0 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: uzp2.8h v3, v0, v1
-; CHECK-NEXT: tbl.16b v0, { v0, v1 }, v2
-; CHECK-NEXT: add.8h v0, v0, v3
+; CHECK-NEXT: uzp1.8h v2, v0, v1
+; CHECK-NEXT: uzp2.8h v0, v0, v1
+; CHECK-NEXT: add.8h v0, v2, v0
; CHECK-NEXT: ret
%tmp3 = shufflevector <8 x i16> %A, <8 x i16> %B, <8 x i32> <i32 undef, i32 undef, i32 4, i32 6, i32 8, i32 10, i32 12, i32 14>
%tmp4 = shufflevector <8 x i16> %A, <8 x i16> %B, <8 x i32> <i32 undef, i32 undef, i32 5, i32 7, i32 9, i32 11, i32 13, i32 15>
@@ -144,13 +136,9 @@ define <8 x i16> @vuzpQi16_undef01(<8 x i16> %A, <8 x i16> %B) nounwind {
define <8 x i16> @vuzpQi16_undef012(<8 x i16> %A, <8 x i16> %B) nounwind {
; CHECK-LABEL: vuzpQi16_undef012:
; CHECK: // %bb.0:
-; CHECK-NEXT: adrp x8, .LCPI10_0
-; CHECK-NEXT: // kill: def $q1 killed $q1 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: ldr q2, [x8, :lo12:.LCPI10_0]
-; CHECK-NEXT: // kill: def $q0 killed $q0 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: uzp2.8h v3, v0, v1
-; CHECK-NEXT: tbl.16b v0, { v0, v1 }, v2
-; CHECK-NEXT: add.8h v0, v0, v3
+; CHECK-NEXT: uzp1.8h v2, v0, v1
+; CHECK-NEXT: uzp2.8h v0, v0, v1
+; CHECK-NEXT: add.8h v0, v2, v0
; CHECK-NEXT: ret
%tmp3 = shufflevector <8 x i16> %A, <8 x i16> %B, <8 x i32> <i32 undef, i32 undef, i32 undef, i32 6, i32 8, i32 10, i32 12, i32 14>
%tmp4 = shufflevector <8 x i16> %A, <8 x i16> %B, <8 x i32> <i32 undef, i32 undef, i32 undef, i32 7, i32 9, i32 11, i32 13, i32 15>
diff --git a/llvm/test/CodeGen/AArch64/arm64-zip.ll b/llvm/test/CodeGen/AArch64/arm64-zip.ll
index 349751dda461f9..4c771cbd2966cc 100644
--- a/llvm/test/CodeGen/AArch64/arm64-zip.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-zip.ll
@@ -142,11 +142,7 @@ define <16 x i8> @vzipQi8_undef(ptr %A, ptr %B) nounwind {
define <8 x i16> @vzip1_undef_01(<8 x i16> %A, <8 x i16> %B) nounwind {
; CHECK-LABEL: vzip1_undef_01:
; CHECK: // %bb.0:
-; CHECK-NEXT: adrp x8, .LCPI8_0
-; CHECK-NEXT: // kill: def $q1 killed $q1 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: ldr q2, [x8, :lo12:.LCPI8_0]
-; CHECK-NEXT: // kill: def $q0 killed $q0 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: tbl.16b v0, { v0, v1 }, v2
+; CHECK-NEXT: zip1.8h v0, v0, v1
; CHECK-NEXT: ret
%s = shufflevector <8 x i16> %A, <8 x i16> %B, <8 x i32> <i32 undef, i32 undef, i32 1, i32 9, i32 2, i32 10, i32 3, i32 11>
ret <8 x i16> %s
@@ -155,11 +151,7 @@ define <8 x i16> @vzip1_undef_01(<8 x i16> %A, <8 x i16> %B) nounwind {
define <8 x i16> @vzip1_undef_0(<8 x i16> %A, <8 x i16> %B) nounwind {
; CHECK-LABEL: vzip1_undef_0:
; CHECK: // %bb.0:
-; CHECK-NEXT: adrp x8, .LCPI9_0
-; CHECK-NEXT: // kill: def $q1 killed $q1 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: ldr q2, [x8, :lo12:.LCPI9_0]
-; CHECK-NEXT: // kill: def $q0 killed $q0 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: tbl.16b v0, { v0, v1 }, v2
+; CHECK-NEXT: zip1.8h v0, v0, v1
; CHECK-NEXT: ret
%s = shufflevector <8 x i16> %A, <8 x i16> %B, <8 x i32> <i32 undef, i32 8, i32 1, i32 9, i32 2, i32 10, i32 3, i32 11>
ret <8 x i16> %s
@@ -177,11 +169,7 @@ define <8 x i16> @vzip1_undef_1(<8 x i16> %A, <8 x i16> %B) nounwind {
define <8 x i16> @vzip1_undef_012(<8 x i16> %A, <8 x i16> %B) nounwind {
; CHECK-LABEL: vzip1_undef_012:
; CHECK: // %bb.0:
-; CHECK-NEXT: adrp x8, .LCPI11_0
-; CHECK-NEXT: // kill: def $q1 killed $q1 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: ldr q2, [x8, :lo12:.LCPI11_0]
-; CHECK-NEXT: // kill: def $q0 killed $q0 killed $q0_q1 def $q0_q1
-; CHECK-NEXT: tbl.16b v0, { v0, v1 }, v2
+; CHECK-NEXT: zip1.8h v0, v0, v1
; CHECK-NEXT: ret
%s = shufflevector <8 x i16> %A, <8 x i16> %B, <8 x i32> <i32 undef, i32 undef, i32 undef, i32 9, i32 2, i32 10, i32 3, i32 11>
ret <8 x i16> %s
|
SamTebbs33
approved these changes
Apr 22, 2024
Collaborator
SamTebbs33
left a comment
SamTebbs33
left a comment
There was a problem hiding this comment.
Nice change, thank you.
davemgreen
changed the title
ginsbach
added a commit
to ginsbach/llvm-project
that referenced
this pull request
Nov 18, 2025
When the first element of a trn mask is undef, the `isTRNMask` function assumes `WhichResult = 1`. That has a 50% chance of being wrong, so we fail to match some valid trn1/trn2. This patch introduces a more precise test to determine the correct value of `WhichResult`, based on corresponding code in the `isZIPMask` and `isUZPMask` functions. - This change is based on llvm#89578. I'd like to follow it up with a further change along the lines of llvm#167235.
MacDue
pushed a commit
that referenced
this pull request
Nov 19, 2025
When the first element of a trn mask is undef, the `isTRNMask` function assumes `WhichResult = 1`. That has a 50% chance of being wrong, so we fail to match some valid trn1/trn2. This patch introduces a more precise test to determine the correct value of `WhichResult`, based on corresponding code in the `isZIPMask` and `isUZPMask` functions. - This change is based on #89578. I'd like to follow it up with a further change along the lines of #167235.
aadeshps-mcw
pushed a commit
to aadeshps-mcw/llvm-project
that referenced
this pull request
Nov 26, 2025
When the first element of a trn mask is undef, the `isTRNMask` function assumes `WhichResult = 1`. That has a 50% chance of being wrong, so we fail to match some valid trn1/trn2. This patch introduces a more precise test to determine the correct value of `WhichResult`, based on corresponding code in the `isZIPMask` and `isUZPMask` functions. - This change is based on llvm#89578. I'd like to follow it up with a further change along the lines of llvm#167235.
Priyanshu3820
pushed a commit
to Priyanshu3820/llvm-project
that referenced
this pull request
Nov 26, 2025
When the first element of a trn mask is undef, the `isTRNMask` function assumes `WhichResult = 1`. That has a 50% chance of being wrong, so we fail to match some valid trn1/trn2. This patch introduces a more precise test to determine the correct value of `WhichResult`, based on corresponding code in the `isZIPMask` and `isUZPMask` functions. - This change is based on llvm#89578. I'd like to follow it up with a further change along the lines of llvm#167235.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In case the first element of a zip/uzp mask is undef, the isZIPMask and isUZPMask functions have a 50% chance of picking the wrong "WhichResult", meaning they don't match a zip/uzp where they could. This patch alters the matching code to first check for the first non-undef element, to try and get WhichResult correct.