[llvm] Revert "[X86] Remove redundant `cmp` before `adc` after `lzcnt` or `tzcnt`" (PR #210006)
via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 16 01:07:27 PDT 2026
llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-x86
Author: Simon Pilgrim (RKSimon)
<details>
<summary>Changes</summary>
Reverts #<!-- -->208392 - while we investigate a miscompile due to CF/ZF mismatch
---
Full diff: https://github.com/llvm/llvm-project/pull/210006.diff
6 Files Affected:
- (modified) llvm/lib/Target/X86/X86InstrInfo.cpp (-12)
- (modified) llvm/test/CodeGen/X86/bitcnt-load-with-cmov.ll (+3-1)
- (removed) llvm/test/CodeGen/X86/remove-redundant-cmp-lzcnt-i64.ll (-76)
- (removed) llvm/test/CodeGen/X86/remove-redundant-cmp-lzcnt.ll (-186)
- (removed) llvm/test/CodeGen/X86/remove-redundant-cmp-tzcnt-i64.ll (-74)
- (removed) llvm/test/CodeGen/X86/remove-redundant-cmp-tzcnt.ll (-199)
``````````diff
diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 277755b51f6b5..cbbfeb84e5838 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -4993,18 +4993,6 @@ bool X86InstrInfo::isRedundantFlagInstr(const MachineInstr &FlagI,
}
return FlagI.isIdenticalTo(OI);
}
- case X86::LZCNT16rr:
- case X86::LZCNT32rr:
- case X86::LZCNT64rr:
- case X86::TZCNT16rr:
- case X86::TZCNT32rr:
- case X86::TZCNT64rr: {
- if (ImmMask != 0 && !SrcReg2.isValid() && ImmValue == 1 &&
- OI.getOperand(1).isReg() && SrcReg == OI.getOperand(1).getReg()) {
- return true;
- }
- return false;
- }
default:
return false;
}
diff --git a/llvm/test/CodeGen/X86/bitcnt-load-with-cmov.ll b/llvm/test/CodeGen/X86/bitcnt-load-with-cmov.ll
index 0a159143efa74..d3d6b25b60c16 100644
--- a/llvm/test/CodeGen/X86/bitcnt-load-with-cmov.ll
+++ b/llvm/test/CodeGen/X86/bitcnt-load-with-cmov.ll
@@ -101,7 +101,9 @@ define i64 @popcnt64_load_cmov(ptr %p0, i64 %a1) {
define i32 @lzcnt32_no_fold_nonzero_cmp(ptr %p0, i32 %a1) {
; CHECK-LABEL: lzcnt32_no_fold_nonzero_cmp:
; CHECK: # %bb.0:
-; CHECK-NEXT: lzcntl (%rdi), %eax
+; CHECK-NEXT: movl (%rdi), %ecx
+; CHECK-NEXT: lzcntl %ecx, %eax
+; CHECK-NEXT: cmpl $1, %ecx
; CHECK-NEXT: cmovel %esi, %eax
; CHECK-NEXT: retq
%v = load i32, ptr %p0, align 4
diff --git a/llvm/test/CodeGen/X86/remove-redundant-cmp-lzcnt-i64.ll b/llvm/test/CodeGen/X86/remove-redundant-cmp-lzcnt-i64.ll
deleted file mode 100644
index 82d10a5688cfa..0000000000000
--- a/llvm/test/CodeGen/X86/remove-redundant-cmp-lzcnt-i64.ll
+++ /dev/null
@@ -1,76 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
-; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+bmi,+lzcnt | FileCheck %s
-
-define i64 @remove_redundant_cmp_ult_lzcnt_i64(i64 %0) {
-; CHECK-LABEL: remove_redundant_cmp_ult_lzcnt_i64:
-; CHECK: # %bb.0:
-; CHECK-NEXT: lzcntq %rdi, %rax
-; CHECK-NEXT: adcq $0, %rax
-; CHECK-NEXT: retq
- %2 = tail call i64 @llvm.ctlz.i64(i64 %0, i1 false)
- %3 = icmp ult i64 %0, 1
- %4 = zext i1 %3 to i64
- %5 = add nuw nsw i64 %2, %4
- ret i64 %5
-}
-
-define i64 @remove_redundant_cmp_ugt_lzcnt_i64(i64 %0) {
-; CHECK-LABEL: remove_redundant_cmp_ugt_lzcnt_i64:
-; CHECK: # %bb.0:
-; CHECK-NEXT: lzcntq %rdi, %rax
-; CHECK-NEXT: cmpq $2, %rdi
-; CHECK-NEXT: sbbq $-1, %rax
-; CHECK-NEXT: retq
- %2 = tail call i64 @llvm.ctlz.i64(i64 %0, i1 false)
- %3 = icmp ugt i64 %0, 1
- %4 = zext i1 %3 to i64
- %5 = add nuw nsw i64 %2, %4
- ret i64 %5
-}
-
-define i64 @remove_redundant_cmp_ne_lzcnt_i64(i64 %0) {
-; CHECK-LABEL: remove_redundant_cmp_ne_lzcnt_i64:
-; CHECK: # %bb.0:
-; CHECK-NEXT: xorl %eax, %eax
-; CHECK-NEXT: lzcntq %rdi, %rcx
-; CHECK-NEXT: setne %al
-; CHECK-NEXT: addq %rcx, %rax
-; CHECK-NEXT: retq
- %2 = tail call i64 @llvm.ctlz.i64(i64 %0, i1 false)
- %3 = icmp ne i64 %0, 1
- %4 = zext i1 %3 to i64
- %5 = add nuw nsw i64 %2, %4
- ret i64 %5
-}
-
-define i64 @remove_redundant_cmp_sge_lzcnt_i64(i64 %0) {
-; CHECK-LABEL: remove_redundant_cmp_sge_lzcnt_i64:
-; CHECK: # %bb.0:
-; CHECK-NEXT: lzcntq %rdi, %rcx
-; CHECK-NEXT: xorl %eax, %eax
-; CHECK-NEXT: testq %rdi, %rdi
-; CHECK-NEXT: setg %al
-; CHECK-NEXT: addq %rcx, %rax
-; CHECK-NEXT: retq
- %2 = tail call i64 @llvm.ctlz.i64(i64 %0, i1 false)
- %3 = icmp sge i64 %0, 1
- %4 = zext i1 %3 to i64
- %5 = add nuw nsw i64 %2, %4
- ret i64 %5
-}
-
-define i64 @remove_redundant_cmp_sle_lzcnt_i64(i64 %0) {
-; CHECK-LABEL: remove_redundant_cmp_sle_lzcnt_i64:
-; CHECK: # %bb.0:
-; CHECK-NEXT: lzcntq %rdi, %rcx
-; CHECK-NEXT: xorl %eax, %eax
-; CHECK-NEXT: cmpq $2, %rdi
-; CHECK-NEXT: setl %al
-; CHECK-NEXT: addq %rcx, %rax
-; CHECK-NEXT: retq
- %2 = tail call i64 @llvm.ctlz.i64(i64 %0, i1 false)
- %3 = icmp sle i64 %0, 1
- %4 = zext i1 %3 to i64
- %5 = add nuw nsw i64 %2, %4
- ret i64 %5
-}
diff --git a/llvm/test/CodeGen/X86/remove-redundant-cmp-lzcnt.ll b/llvm/test/CodeGen/X86/remove-redundant-cmp-lzcnt.ll
deleted file mode 100644
index 7658e7e96c93c..0000000000000
--- a/llvm/test/CodeGen/X86/remove-redundant-cmp-lzcnt.ll
+++ /dev/null
@@ -1,186 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
-; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+bmi,+lzcnt | FileCheck %s --check-prefix=X64
-; RUN: llc < %s -mtriple=i686-unknown-unknown -mattr=+bmi,+lzcnt | FileCheck %s --check-prefix=X86
-
-define i32 @remove_redundant_cmp_eq_lzcnt_i32(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_eq_lzcnt_i32:
-; X64: # %bb.0:
-; X64-NEXT: lzcntl %edi, %eax
-; X64-NEXT: adcl $0, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_eq_lzcnt_i32:
-; X86: # %bb.0:
-; X86-NEXT: lzcntl {{[0-9]+}}(%esp), %eax
-; X86-NEXT: adcl $0, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.ctlz.i32(i32 %0, i1 false)
- %3 = icmp eq i32 %0, 0
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
-
-define i32 @remove_redundant_cmp_uge_lzcnt_i32(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_uge_lzcnt_i32:
-; X64: # %bb.0:
-; X64-NEXT: lzcntl %edi, %eax
-; X64-NEXT: sbbl $-1, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_uge_lzcnt_i32:
-; X86: # %bb.0:
-; X86-NEXT: lzcntl {{[0-9]+}}(%esp), %eax
-; X86-NEXT: sbbl $-1, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.ctlz.i32(i32 %0, i1 false)
- %3 = icmp uge i32 %0, 1
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
-
-define i32 @remove_redundant_cmp_ule_lzcnt_i32(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_ule_lzcnt_i32:
-; X64: # %bb.0:
-; X64-NEXT: lzcntl %edi, %eax
-; X64-NEXT: cmpl $2, %edi
-; X64-NEXT: adcl $0, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_ule_lzcnt_i32:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: lzcntl %ecx, %eax
-; X86-NEXT: cmpl $2, %ecx
-; X86-NEXT: adcl $0, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.ctlz.i32(i32 %0, i1 false)
- %3 = icmp ule i32 %0, 1
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
-
-define i32 @remove_redundant_cmp_slt_lzcnt_i32(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_slt_lzcnt_i32:
-; X64: # %bb.0:
-; X64-NEXT: lzcntl %edi, %ecx
-; X64-NEXT: xorl %eax, %eax
-; X64-NEXT: testl %edi, %edi
-; X64-NEXT: setle %al
-; X64-NEXT: addl %ecx, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_slt_lzcnt_i32:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: lzcntl %ecx, %edx
-; X86-NEXT: xorl %eax, %eax
-; X86-NEXT: testl %ecx, %ecx
-; X86-NEXT: setle %al
-; X86-NEXT: addl %edx, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.ctlz.i32(i32 %0, i1 false)
- %3 = icmp slt i32 %0, 1
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
-
-define i32 @remove_redundant_cmp_sgt_lzcnt_i32(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_sgt_lzcnt_i32:
-; X64: # %bb.0:
-; X64-NEXT: lzcntl %edi, %ecx
-; X64-NEXT: xorl %eax, %eax
-; X64-NEXT: cmpl $2, %edi
-; X64-NEXT: setge %al
-; X64-NEXT: addl %ecx, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_sgt_lzcnt_i32:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: lzcntl %ecx, %edx
-; X86-NEXT: xorl %eax, %eax
-; X86-NEXT: cmpl $2, %ecx
-; X86-NEXT: setge %al
-; X86-NEXT: addl %edx, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.ctlz.i32(i32 %0, i1 false)
- %3 = icmp sgt i32 %0, 1
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
-
-define i16 @remove_redundant_cmp_lzcnt_i16(i16 %0) {
-; X64-LABEL: remove_redundant_cmp_lzcnt_i16:
-; X64: # %bb.0:
-; X64-NEXT: lzcntw %di, %ax
-; X64-NEXT: adcw $0, %ax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_lzcnt_i16:
-; X86: # %bb.0:
-; X86-NEXT: lzcntw {{[0-9]+}}(%esp), %ax
-; X86-NEXT: adcw $0, %ax
-; X86-NEXT: retl
- %2 = tail call i16 @llvm.ctlz.i16(i16 %0, i1 false)
- %3 = icmp eq i16 %0, 0
- %4 = zext i1 %3 to i16
- %5 = add nuw nsw i16 %2, %4
- ret i16 %5
-}
-
-define i32 @remove_redundant_cmp_lzcnt_no_constant(i32 %0, i32 %1) {
-; X64-LABEL: remove_redundant_cmp_lzcnt_no_constant:
-; X64: # %bb.0:
-; X64-NEXT: lzcntl %edi, %ecx
-; X64-NEXT: xorl %eax, %eax
-; X64-NEXT: cmpl %esi, %edi
-; X64-NEXT: sete %al
-; X64-NEXT: addl %ecx, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_lzcnt_no_constant:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: lzcntl %ecx, %edx
-; X86-NEXT: xorl %eax, %eax
-; X86-NEXT: cmpl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: sete %al
-; X86-NEXT: addl %edx, %eax
-; X86-NEXT: retl
- %3 = tail call i32 @llvm.ctlz.i32(i32 %0, i1 false)
- %4 = icmp eq i32 %0, %1
- %5 = zext i1 %4 to i32
- %6 = add nuw nsw i32 %3, %5
- ret i32 %6
-}
-
-define i32 @remove_redundant_cmp_lzcnt_wrong_const(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_lzcnt_wrong_const:
-; X64: # %bb.0:
-; X64-NEXT: lzcntl %edi, %ecx
-; X64-NEXT: xorl %eax, %eax
-; X64-NEXT: cmpl $2, %edi
-; X64-NEXT: sete %al
-; X64-NEXT: addl %ecx, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_lzcnt_wrong_const:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: lzcntl %ecx, %edx
-; X86-NEXT: xorl %eax, %eax
-; X86-NEXT: cmpl $2, %ecx
-; X86-NEXT: sete %al
-; X86-NEXT: addl %edx, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.ctlz.i32(i32 %0, i1 false)
- %3 = icmp eq i32 %0, 2
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
diff --git a/llvm/test/CodeGen/X86/remove-redundant-cmp-tzcnt-i64.ll b/llvm/test/CodeGen/X86/remove-redundant-cmp-tzcnt-i64.ll
deleted file mode 100644
index a378156c639ef..0000000000000
--- a/llvm/test/CodeGen/X86/remove-redundant-cmp-tzcnt-i64.ll
+++ /dev/null
@@ -1,74 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
-; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+bmi,+lzcnt | FileCheck %s
-
-define i64 @remove_redundant_cmp_eq_tzcnt_i64(i64 %0) {
-; CHECK-LABEL: remove_redundant_cmp_eq_tzcnt_i64:
-; CHECK: # %bb.0:
-; CHECK-NEXT: tzcntq %rdi, %rax
-; CHECK-NEXT: adcq $0, %rax
-; CHECK-NEXT: retq
- %2 = tail call i64 @llvm.cttz.i64(i64 %0, i1 false)
- %3 = icmp eq i64 %0, 0
- %4 = zext i1 %3 to i64
- %5 = add nuw nsw i64 %2, %4
- ret i64 %5
-}
-
-define i64 @remove_redundant_cmp_uge_tzcnt_i64(i64 %0) {
-; CHECK-LABEL: remove_redundant_cmp_uge_tzcnt_i64:
-; CHECK: # %bb.0:
-; CHECK-NEXT: tzcntq %rdi, %rax
-; CHECK-NEXT: sbbq $-1, %rax
-; CHECK-NEXT: retq
- %2 = tail call i64 @llvm.cttz.i64(i64 %0, i1 false)
- %3 = icmp uge i64 %0, 1
- %4 = zext i1 %3 to i64
- %5 = add nuw nsw i64 %2, %4
- ret i64 %5
-}
-
-define i64 @remove_redundant_cmp_ule_tzcnt_i64(i64 %0) {
-; CHECK-LABEL: remove_redundant_cmp_ule_tzcnt_i64:
-; CHECK: # %bb.0:
-; CHECK-NEXT: tzcntq %rdi, %rax
-; CHECK-NEXT: cmpq $2, %rdi
-; CHECK-NEXT: adcq $0, %rax
-; CHECK-NEXT: retq
- %2 = tail call i64 @llvm.cttz.i64(i64 %0, i1 false)
- %3 = icmp ule i64 %0, 1
- %4 = zext i1 %3 to i64
- %5 = add nuw nsw i64 %2, %4
- ret i64 %5
-}
-
-define i64 @remove_redundant_cmp_slt_tzcnt_i64(i64 %0) {
-; CHECK-LABEL: remove_redundant_cmp_slt_tzcnt_i64:
-; CHECK: # %bb.0:
-; CHECK-NEXT: tzcntq %rdi, %rcx
-; CHECK-NEXT: xorl %eax, %eax
-; CHECK-NEXT: testq %rdi, %rdi
-; CHECK-NEXT: setle %al
-; CHECK-NEXT: addq %rcx, %rax
-; CHECK-NEXT: retq
- %2 = tail call i64 @llvm.cttz.i64(i64 %0, i1 false)
- %3 = icmp slt i64 %0, 1
- %4 = zext i1 %3 to i64
- %5 = add nuw nsw i64 %2, %4
- ret i64 %5
-}
-
-define i64 @remove_redundant_cmp_sgt_tzcnt_i64(i64 %0) {
-; CHECK-LABEL: remove_redundant_cmp_sgt_tzcnt_i64:
-; CHECK: # %bb.0:
-; CHECK-NEXT: tzcntq %rdi, %rcx
-; CHECK-NEXT: xorl %eax, %eax
-; CHECK-NEXT: cmpq $2, %rdi
-; CHECK-NEXT: setge %al
-; CHECK-NEXT: addq %rcx, %rax
-; CHECK-NEXT: retq
- %2 = tail call i64 @llvm.cttz.i64(i64 %0, i1 false)
- %3 = icmp sgt i64 %0, 1
- %4 = zext i1 %3 to i64
- %5 = add nuw nsw i64 %2, %4
- ret i64 %5
-}
diff --git a/llvm/test/CodeGen/X86/remove-redundant-cmp-tzcnt.ll b/llvm/test/CodeGen/X86/remove-redundant-cmp-tzcnt.ll
deleted file mode 100644
index 0dee74e413066..0000000000000
--- a/llvm/test/CodeGen/X86/remove-redundant-cmp-tzcnt.ll
+++ /dev/null
@@ -1,199 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
-; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+bmi,+lzcnt | FileCheck %s --check-prefix=X64
-; RUN: llc < %s -mtriple=i686-unknown-unknown -mattr=+bmi,+lzcnt | FileCheck %s --check-prefix=X86
-
-define i32 @remove_redundant_cmp_ult_tzcnt_i32(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_ult_tzcnt_i32:
-; X64: # %bb.0:
-; X64-NEXT: tzcntl %edi, %eax
-; X64-NEXT: adcl $0, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_ult_tzcnt_i32:
-; X86: # %bb.0:
-; X86-NEXT: tzcntl {{[0-9]+}}(%esp), %eax
-; X86-NEXT: adcl $0, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.cttz.i32(i32 %0, i1 false)
- %3 = icmp ult i32 %0, 1
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
-
-define i32 @remove_redundant_cmp_ugt_tzcnt_i32(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_ugt_tzcnt_i32:
-; X64: # %bb.0:
-; X64-NEXT: tzcntl %edi, %eax
-; X64-NEXT: cmpl $2, %edi
-; X64-NEXT: sbbl $-1, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_ugt_tzcnt_i32:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: tzcntl %ecx, %eax
-; X86-NEXT: cmpl $2, %ecx
-; X86-NEXT: sbbl $-1, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.cttz.i32(i32 %0, i1 false)
- %3 = icmp ugt i32 %0, 1
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
-
-define i32 @remove_redundant_cmp_ne_tzcnt_i32(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_ne_tzcnt_i32:
-; X64: # %bb.0:
-; X64-NEXT: xorl %eax, %eax
-; X64-NEXT: tzcntl %edi, %ecx
-; X64-NEXT: setne %al
-; X64-NEXT: addl %ecx, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_ne_tzcnt_i32:
-; X86: # %bb.0:
-; X86-NEXT: xorl %eax, %eax
-; X86-NEXT: tzcntl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: setne %al
-; X86-NEXT: addl %ecx, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.cttz.i32(i32 %0, i1 false)
- %3 = icmp ne i32 %0, 1
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
-
-define i32 @remove_redundant_cmp_sge_tzcnt_i32(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_sge_tzcnt_i32:
-; X64: # %bb.0:
-; X64-NEXT: tzcntl %edi, %ecx
-; X64-NEXT: xorl %eax, %eax
-; X64-NEXT: testl %edi, %edi
-; X64-NEXT: setg %al
-; X64-NEXT: addl %ecx, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_sge_tzcnt_i32:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: tzcntl %ecx, %edx
-; X86-NEXT: xorl %eax, %eax
-; X86-NEXT: testl %ecx, %ecx
-; X86-NEXT: setg %al
-; X86-NEXT: addl %edx, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.cttz.i32(i32 %0, i1 false)
- %3 = icmp sge i32 %0, 1
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
-
-define i32 @remove_redundant_cmp_sle_tzcnt_i32(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_sle_tzcnt_i32:
-; X64: # %bb.0:
-; X64-NEXT: tzcntl %edi, %ecx
-; X64-NEXT: xorl %eax, %eax
-; X64-NEXT: cmpl $2, %edi
-; X64-NEXT: setl %al
-; X64-NEXT: addl %ecx, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_sle_tzcnt_i32:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: tzcntl %ecx, %edx
-; X86-NEXT: xorl %eax, %eax
-; X86-NEXT: cmpl $2, %ecx
-; X86-NEXT: setl %al
-; X86-NEXT: addl %edx, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.cttz.i32(i32 %0, i1 false)
- %3 = icmp sle i32 %0, 1
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
-
-define i16 @remove_redundant_cmp_tzcnt_i16(i16 %0) {
-; X64-LABEL: remove_redundant_cmp_tzcnt_i16:
-; X64: # %bb.0:
-; X64-NEXT: movl %edi, %eax
-; X64-NEXT: orl $65536, %eax # imm = 0x10000
-; X64-NEXT: tzcntl %eax, %eax
-; X64-NEXT: cmpw $1, %di
-; X64-NEXT: adcw $0, %ax
-; X64-NEXT: # kill: def $ax killed $ax killed $eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_tzcnt_i16:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: movl %ecx, %eax
-; X86-NEXT: orl $65536, %eax # imm = 0x10000
-; X86-NEXT: tzcntl %eax, %eax
-; X86-NEXT: cmpw $1, %cx
-; X86-NEXT: adcw $0, %ax
-; X86-NEXT: # kill: def $ax killed $ax killed $eax
-; X86-NEXT: retl
- %2 = tail call i16 @llvm.cttz.i16(i16 %0, i1 false)
- %3 = icmp eq i16 %0, 0
- %4 = zext i1 %3 to i16
- %5 = add nuw nsw i16 %2, %4
- ret i16 %5
-}
-
-define i32 @remove_redundant_cmp_tzcnt_no_constant(i32 %0, i32 %1) {
-; X64-LABEL: remove_redundant_cmp_tzcnt_no_constant:
-; X64: # %bb.0:
-; X64-NEXT: tzcntl %edi, %ecx
-; X64-NEXT: xorl %eax, %eax
-; X64-NEXT: cmpl %esi, %edi
-; X64-NEXT: sete %al
-; X64-NEXT: addl %ecx, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_tzcnt_no_constant:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: tzcntl %ecx, %edx
-; X86-NEXT: xorl %eax, %eax
-; X86-NEXT: cmpl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: sete %al
-; X86-NEXT: addl %edx, %eax
-; X86-NEXT: retl
- %3 = tail call i32 @llvm.cttz.i32(i32 %0, i1 false)
- %4 = icmp eq i32 %0, %1
- %5 = zext i1 %4 to i32
- %6 = add nuw nsw i32 %3, %5
- ret i32 %6
-}
-
-define i32 @remove_redundant_cmp_tzcnt_wrong_const(i32 %0) {
-; X64-LABEL: remove_redundant_cmp_tzcnt_wrong_const:
-; X64: # %bb.0:
-; X64-NEXT: tzcntl %edi, %ecx
-; X64-NEXT: xorl %eax, %eax
-; X64-NEXT: cmpl $2, %edi
-; X64-NEXT: sete %al
-; X64-NEXT: addl %ecx, %eax
-; X64-NEXT: retq
-;
-; X86-LABEL: remove_redundant_cmp_tzcnt_wrong_const:
-; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT: tzcntl %ecx, %edx
-; X86-NEXT: xorl %eax, %eax
-; X86-NEXT: cmpl $2, %ecx
-; X86-NEXT: sete %al
-; X86-NEXT: addl %edx, %eax
-; X86-NEXT: retl
- %2 = tail call i32 @llvm.cttz.i32(i32 %0, i1 false)
- %3 = icmp eq i32 %0, 2
- %4 = zext i1 %3 to i32
- %5 = add nuw nsw i32 %2, %4
- ret i32 %5
-}
``````````
</details>
https://github.com/llvm/llvm-project/pull/210006
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