llvm/test/CodeGen/X86/bit_ceil.ll

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=-bmi2,-lzcnt | FileCheck %s --check-prefix=NOBMI
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+bmi2,+lzcnt | FileCheck %s --check-prefix=BMI

; Check the assembly sequence generated for std::bit_ceil.

; std::bit_ceil<uint32_t>(x)
define i32 @bit_ceil_i32(i32 %x) {
; NOBMI-LABEL: bit_ceil_i32:
; NOBMI:       # %bb.0:
; NOBMI-NEXT:    # kill: def $edi killed $edi def $rdi
; NOBMI-NEXT:    leal -1(%rdi), %eax
; NOBMI-NEXT:    movl $63, %ecx
; NOBMI-NEXT:    bsrl %eax, %ecx
; NOBMI-NEXT:    xorl $31, %ecx
; NOBMI-NEXT:    negb %cl
; NOBMI-NEXT:    movl $1, %edx
; NOBMI-NEXT:    movl $1, %eax
; NOBMI-NEXT:    # kill: def $cl killed $cl killed $ecx
; NOBMI-NEXT:    shll %cl, %eax
; NOBMI-NEXT:    cmpl $2, %edi
; NOBMI-NEXT:    cmovbl %edx, %eax
; NOBMI-NEXT:    retq
;
; BMI-LABEL: bit_ceil_i32:
; BMI:       # %bb.0:
; BMI-NEXT:    # kill: def $edi killed $edi def $rdi
; BMI-NEXT:    leal -1(%rdi), %eax
; BMI-NEXT:    lzcntl %eax, %eax
; BMI-NEXT:    negb %al
; BMI-NEXT:    movl $1, %ecx
; BMI-NEXT:    shlxl %eax, %ecx, %eax
; BMI-NEXT:    cmpl $2, %edi
; BMI-NEXT:    cmovbl %ecx, %eax
; BMI-NEXT:    retq
  %dec = add i32 %x, -1
  %lz = tail call i32 @llvm.ctlz.i32(i32 %dec, i1 false)
  %cnt = sub i32 32, %lz
  %res = shl i32 1, %cnt
  %ugt = icmp ugt i32 %x, 1
  %sel = select i1 %ugt, i32 %res, i32 1
  ret i32 %sel
}

; std::bit_ceil<uint32_t>(x + 1)
define i32 @bit_ceil_i32_plus1(i32 noundef %x) {
; NOBMI-LABEL: bit_ceil_i32_plus1:
; NOBMI:       # %bb.0: # %entry
; NOBMI-NEXT:    movl $63, %ecx
; NOBMI-NEXT:    bsrl %edi, %ecx
; NOBMI-NEXT:    xorl $31, %ecx
; NOBMI-NEXT:    negb %cl
; NOBMI-NEXT:    movl $1, %edx
; NOBMI-NEXT:    movl $1, %eax
; NOBMI-NEXT:    # kill: def $cl killed $cl killed $ecx
; NOBMI-NEXT:    shll %cl, %eax
; NOBMI-NEXT:    decl %edi
; NOBMI-NEXT:    cmpl $-2, %edi
; NOBMI-NEXT:    cmovael %edx, %eax
; NOBMI-NEXT:    retq
;
; BMI-LABEL: bit_ceil_i32_plus1:
; BMI:       # %bb.0: # %entry
; BMI-NEXT:    lzcntl %edi, %eax
; BMI-NEXT:    negb %al
; BMI-NEXT:    movl $1, %ecx
; BMI-NEXT:    shlxl %eax, %ecx, %eax
; BMI-NEXT:    decl %edi
; BMI-NEXT:    cmpl $-2, %edi
; BMI-NEXT:    cmovael %ecx, %eax
; BMI-NEXT:    retq
entry:
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 false)
  %cnt = sub i32 32, %ctlz
  %shl = shl i32 1, %cnt
  %dec = add i32 %x, -1
  %ult = icmp ult i32 %dec, -2
  %sel = select i1 %ult, i32 %shl, i32 1
  ret i32 %sel
}

; std::bit_ceil<uint64_t>(x)
define i64 @bit_ceil_i64(i64 %x) {
; NOBMI-LABEL: bit_ceil_i64:
; NOBMI:       # %bb.0:
; NOBMI-NEXT:    leaq -1(%rdi), %rax
; NOBMI-NEXT:    movl $127, %ecx
; NOBMI-NEXT:    bsrq %rax, %rcx
; NOBMI-NEXT:    xorl $63, %ecx
; NOBMI-NEXT:    negb %cl
; NOBMI-NEXT:    movl $1, %edx
; NOBMI-NEXT:    movl $1, %eax
; NOBMI-NEXT:    # kill: def $cl killed $cl killed $rcx
; NOBMI-NEXT:    shlq %cl, %rax
; NOBMI-NEXT:    cmpq $2, %rdi
; NOBMI-NEXT:    cmovbq %rdx, %rax
; NOBMI-NEXT:    retq
;
; BMI-LABEL: bit_ceil_i64:
; BMI:       # %bb.0:
; BMI-NEXT:    leaq -1(%rdi), %rax
; BMI-NEXT:    lzcntq %rax, %rax
; BMI-NEXT:    negb %al
; BMI-NEXT:    movl $1, %ecx
; BMI-NEXT:    shlxq %rax, %rcx, %rax
; BMI-NEXT:    cmpq $2, %rdi
; BMI-NEXT:    cmovbq %rcx, %rax
; BMI-NEXT:    retq
  %dec = add i64 %x, -1
  %lz = tail call i64 @llvm.ctlz.i64(i64 %dec, i1 false)
  %cnt = sub i64 64, %lz
  %res = shl i64 1, %cnt
  %ugt = icmp ugt i64 %x, 1
  %sel = select i1 %ugt, i64 %res, i64 1
  ret i64 %sel
}

; std::bit_ceil<uint64_t>(x + 1)
define i64 @bit_ceil_i64_plus1(i64 noundef %x) {
; NOBMI-LABEL: bit_ceil_i64_plus1:
; NOBMI:       # %bb.0: # %entry
; NOBMI-NEXT:    movl $127, %ecx
; NOBMI-NEXT:    bsrq %rdi, %rcx
; NOBMI-NEXT:    xorl $63, %ecx
; NOBMI-NEXT:    negb %cl
; NOBMI-NEXT:    movl $1, %edx
; NOBMI-NEXT:    movl $1, %eax
; NOBMI-NEXT:    # kill: def $cl killed $cl killed $rcx
; NOBMI-NEXT:    shlq %cl, %rax
; NOBMI-NEXT:    decq %rdi
; NOBMI-NEXT:    cmpq $-2, %rdi
; NOBMI-NEXT:    cmovaeq %rdx, %rax
; NOBMI-NEXT:    retq
;
; BMI-LABEL: bit_ceil_i64_plus1:
; BMI:       # %bb.0: # %entry
; BMI-NEXT:    lzcntq %rdi, %rax
; BMI-NEXT:    negb %al
; BMI-NEXT:    movl $1, %ecx
; BMI-NEXT:    shlxq %rax, %rcx, %rax
; BMI-NEXT:    decq %rdi
; BMI-NEXT:    cmpq $-2, %rdi
; BMI-NEXT:    cmovaeq %rcx, %rax
; BMI-NEXT:    retq
entry:
  %ctlz = tail call i64 @llvm.ctlz.i64(i64 %x, i1 false)
  %cnt = sub i64 64, %ctlz
  %shl = shl i64 1, %cnt
  %dec = add i64 %x, -1
  %ult = icmp ult i64 %dec, -2
  %sel = select i1 %ult, i64 %shl, i64 1
  ret i64 %sel
}

declare i32 @llvm.ctlz.i32(i32, i1 immarg)
declare i64 @llvm.ctlz.i64(i64, i1 immarg)