https://github.com/llvmbot created
https://github.com/llvm/llvm-project/pull/108783
Backport 1c378d2b145578948942512f9d6985e37659d013
81279bf97f187eee0446af00d8ae9ec32a22e878
Requested by: @goldsteinn
>From 4c558a8d535a48d0588671d1574bc5a70478adce Mon Sep 17 00:00:00 2001
From: Noah Goldstein <goldstein....@gmail.com>
Date: Sun, 15 Sep 2024 09:00:28 -0700
Subject: [PATCH 1/2] [X86] Add test for issue 108722; NFC
(cherry picked from commit 1c378d2b145578948942512f9d6985e37659d013)
---
llvm/test/CodeGen/X86/cmp-shiftX-maskX.ll | 24 +++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/llvm/test/CodeGen/X86/cmp-shiftX-maskX.ll
b/llvm/test/CodeGen/X86/cmp-shiftX-maskX.ll
index 67070b989786db..799b5417857575 100644
--- a/llvm/test/CodeGen/X86/cmp-shiftX-maskX.ll
+++ b/llvm/test/CodeGen/X86/cmp-shiftX-maskX.ll
@@ -994,6 +994,30 @@ define i1 @shr_to_rotate_eq_i32_s5(i32 %x) {
ret i1 %r
}
+define i32 @issue108722(i32 %0) {
+; CHECK-NOBMI-LABEL: issue108722:
+; CHECK-NOBMI: # %bb.0:
+; CHECK-NOBMI-NEXT: movzbl %dil, %ecx
+; CHECK-NOBMI-NEXT: shrl $24, %edi
+; CHECK-NOBMI-NEXT: xorl %eax, %eax
+; CHECK-NOBMI-NEXT: cmpl %edi, %ecx
+; CHECK-NOBMI-NEXT: sete %al
+; CHECK-NOBMI-NEXT: retq
+;
+; CHECK-BMI2-LABEL: issue108722:
+; CHECK-BMI2: # %bb.0:
+; CHECK-BMI2-NEXT: rorxl $8, %edi, %ecx
+; CHECK-BMI2-NEXT: xorl %eax, %eax
+; CHECK-BMI2-NEXT: cmpl %edi, %ecx
+; CHECK-BMI2-NEXT: sete %al
+; CHECK-BMI2-NEXT: retq
+ %2 = tail call i32 @llvm.fshl.i32(i32 %0, i32 %0, i32 24)
+ %3 = icmp eq i32 %2, %0
+ %4 = zext i1 %3 to i32
+ ret i32 %4
+}
+
+
;; NOTE: These prefixes are unused and the list is autogenerated. Do not add
tests below this line:
; CHECK-AVX: {{.*}}
; CHECK-NOBMI-SSE2: {{.*}}
>From 7aaa237104f50ba921d05a371be00636ed700e14 Mon Sep 17 00:00:00 2001
From: Noah Goldstein <goldstein....@gmail.com>
Date: Sun, 15 Sep 2024 09:00:34 -0700
Subject: [PATCH 2/2] [X86] Fix missing check of rotate <-> shift equivilence
(Issue 108722)
Previous code was checking that rotate and shift where equivilent when
transforming shift -> rotate but not the other way around.
Closes #108767
(cherry picked from commit 81279bf97f187eee0446af00d8ae9ec32a22e878)
---
llvm/lib/Target/X86/X86ISelLowering.cpp | 2 +-
llvm/test/CodeGen/X86/cmp-shiftX-maskX.ll | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp
b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 5a9d679d7002cb..45989bcd07d37e 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -3415,7 +3415,7 @@ unsigned
X86TargetLowering::preferedOpcodeForCmpEqPiecesOfOperand(
// We prefer rotate for vectors of if we won't get a zext mask with SRL
// (PreferRotate will be set in the latter case).
- if (PreferRotate || VT.isVector())
+ if (PreferRotate || !MayTransformRotate || VT.isVector())
return ShiftOpc;
// Non-vector type and we have a zext mask with SRL.
diff --git a/llvm/test/CodeGen/X86/cmp-shiftX-maskX.ll
b/llvm/test/CodeGen/X86/cmp-shiftX-maskX.ll
index 799b5417857575..227de9ad0ab690 100644
--- a/llvm/test/CodeGen/X86/cmp-shiftX-maskX.ll
+++ b/llvm/test/CodeGen/X86/cmp-shiftX-maskX.ll
@@ -997,8 +997,8 @@ define i1 @shr_to_rotate_eq_i32_s5(i32 %x) {
define i32 @issue108722(i32 %0) {
; CHECK-NOBMI-LABEL: issue108722:
; CHECK-NOBMI: # %bb.0:
-; CHECK-NOBMI-NEXT: movzbl %dil, %ecx
-; CHECK-NOBMI-NEXT: shrl $24, %edi
+; CHECK-NOBMI-NEXT: movl %edi, %ecx
+; CHECK-NOBMI-NEXT: roll $24, %ecx
; CHECK-NOBMI-NEXT: xorl %eax, %eax
; CHECK-NOBMI-NEXT: cmpl %edi, %ecx
; CHECK-NOBMI-NEXT: sete %al
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