; 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(x) define i32 @bit_ceil_i32(i32 %x) { ; NOBMI-LABEL: bit_ceil_i32: ; NOBMI: # %bb.0: ; NOBMI-NEXT: movl %edi, %eax ; NOBMI-NEXT: decl %eax ; NOBMI-NEXT: je .LBB0_1 ; NOBMI-NEXT: # %bb.2: # %cond.false ; NOBMI-NEXT: bsrl %eax, %ecx ; NOBMI-NEXT: xorl $31, %ecx ; NOBMI-NEXT: jmp .LBB0_3 ; NOBMI-NEXT: .LBB0_1: ; NOBMI-NEXT: movl $32, %ecx ; NOBMI-NEXT: .LBB0_3: # %cond.end ; 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(x + 1) define i32 @bit_ceil_i32_plus1(i32 noundef %x) { ; NOBMI-LABEL: bit_ceil_i32_plus1: ; NOBMI: # %bb.0: # %entry ; NOBMI-NEXT: testl %edi, %edi ; NOBMI-NEXT: je .LBB1_1 ; NOBMI-NEXT: # %bb.2: # %cond.false ; NOBMI-NEXT: bsrl %edi, %ecx ; NOBMI-NEXT: xorl $31, %ecx ; NOBMI-NEXT: jmp .LBB1_3 ; NOBMI-NEXT: .LBB1_1: ; NOBMI-NEXT: movl $32, %ecx ; NOBMI-NEXT: .LBB1_3: # %cond.end ; 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(x) define i64 @bit_ceil_i64(i64 %x) { ; NOBMI-LABEL: bit_ceil_i64: ; NOBMI: # %bb.0: ; NOBMI-NEXT: movq %rdi, %rax ; NOBMI-NEXT: decq %rax ; NOBMI-NEXT: je .LBB2_1 ; NOBMI-NEXT: # %bb.2: # %cond.false ; NOBMI-NEXT: bsrq %rax, %rcx ; NOBMI-NEXT: xorq $63, %rcx ; NOBMI-NEXT: jmp .LBB2_3 ; NOBMI-NEXT: .LBB2_1: ; NOBMI-NEXT: movl $64, %ecx ; NOBMI-NEXT: .LBB2_3: # %cond.end ; 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(x + 1) define i64 @bit_ceil_i64_plus1(i64 noundef %x) { ; NOBMI-LABEL: bit_ceil_i64_plus1: ; NOBMI: # %bb.0: # %entry ; NOBMI-NEXT: testq %rdi, %rdi ; NOBMI-NEXT: je .LBB3_1 ; NOBMI-NEXT: # %bb.2: # %cond.false ; NOBMI-NEXT: bsrq %rdi, %rcx ; NOBMI-NEXT: xorq $63, %rcx ; NOBMI-NEXT: jmp .LBB3_3 ; NOBMI-NEXT: .LBB3_1: ; NOBMI-NEXT: movl $64, %ecx ; NOBMI-NEXT: .LBB3_3: # %cond.end ; 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)