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llvm-project/llvm/test/CodeGen/X86/ssub_sat_plus.ll
David Green d10f23a25d [ISel] Expand saddsat and ssubsat via asr and xor 
This changes the lowering of saddsat and ssubsat so that instead of
using:
  r,o = saddo x, y
  c = setcc r < 0
  s = c ? INTMAX : INTMIN
  ret o ? s : r
into using asr and xor to materialize the INTMAX/INTMIN constants:
  r,o = saddo x, y
  s = ashr r, BW-1
  x = xor s, INTMIN
  ret o ? x : r
https://alive2.llvm.org/ce/z/TYufgD

This seems to reduce the instruction count in most testcases across most
architectures. X86 has some custom lowering added to compensate for
cases where it can increase instruction count.

Differential Revision: https://reviews.llvm.org/D105853
2021-08-19 16:08:07 +01:00

180 lines
5.4 KiB
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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=i686 -mattr=cmov | FileCheck %s --check-prefix=X86
; RUN: llc < %s -mtriple=x86_64-linux | FileCheck %s --check-prefix=X64
declare i4 @llvm.ssub.sat.i4(i4, i4)
declare i8 @llvm.ssub.sat.i8(i8, i8)
declare i16 @llvm.ssub.sat.i16(i16, i16)
declare i32 @llvm.ssub.sat.i32(i32, i32)
declare i64 @llvm.ssub.sat.i64(i64, i64)
define i32 @func32(i32 %x, i32 %y, i32 %z) nounwind {
; X86-LABEL: func32:
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
; X86-NEXT: movl {{[0-9]+}}(%esp), %edx
; X86-NEXT: imull {{[0-9]+}}(%esp), %edx
; X86-NEXT: xorl %ecx, %ecx
; X86-NEXT: cmpl %edx, %eax
; X86-NEXT: setns %cl
; X86-NEXT: addl $2147483647, %ecx # imm = 0x7FFFFFFF
; X86-NEXT: subl %edx, %eax
; X86-NEXT: cmovol %ecx, %eax
; X86-NEXT: retl
;
; X64-LABEL: func32:
; X64: # %bb.0:
; X64-NEXT: imull %edx, %esi
; X64-NEXT: xorl %eax, %eax
; X64-NEXT: cmpl %esi, %edi
; X64-NEXT: setns %al
; X64-NEXT: addl $2147483647, %eax # imm = 0x7FFFFFFF
; X64-NEXT: subl %esi, %edi
; X64-NEXT: cmovnol %edi, %eax
; X64-NEXT: retq
%a = mul i32 %y, %z
%tmp = call i32 @llvm.ssub.sat.i32(i32 %x, i32 %a)
ret i32 %tmp
}
define i64 @func64(i64 %x, i64 %y, i64 %z) nounwind {
; X86-LABEL: func64:
; X86: # %bb.0:
; X86-NEXT: pushl %ebx
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: subl {{[0-9]+}}(%esp), %eax
; X86-NEXT: sbbl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: seto %bl
; X86-NEXT: movl %ecx, %edx
; X86-NEXT: sarl $31, %edx
; X86-NEXT: testb %bl, %bl
; X86-NEXT: cmovnel %edx, %eax
; X86-NEXT: xorl $-2147483648, %edx # imm = 0x80000000
; X86-NEXT: testb %bl, %bl
; X86-NEXT: cmovel %ecx, %edx
; X86-NEXT: popl %ebx
; X86-NEXT: retl
;
; X64-LABEL: func64:
; X64: # %bb.0:
; X64-NEXT: xorl %ecx, %ecx
; X64-NEXT: cmpq %rdx, %rdi
; X64-NEXT: setns %cl
; X64-NEXT: movabsq $9223372036854775807, %rax # imm = 0x7FFFFFFFFFFFFFFF
; X64-NEXT: addq %rcx, %rax
; X64-NEXT: subq %rdx, %rdi
; X64-NEXT: cmovnoq %rdi, %rax
; X64-NEXT: retq
%a = mul i64 %y, %z
%tmp = call i64 @llvm.ssub.sat.i64(i64 %x, i64 %z)
ret i64 %tmp
}
define signext i16 @func16(i16 signext %x, i16 signext %y, i16 signext %z) nounwind {
; X86-LABEL: func16:
; X86: # %bb.0:
; X86-NEXT: movzwl {{[0-9]+}}(%esp), %eax
; X86-NEXT: movzwl {{[0-9]+}}(%esp), %edx
; X86-NEXT: imulw {{[0-9]+}}(%esp), %dx
; X86-NEXT: xorl %ecx, %ecx
; X86-NEXT: cmpw %dx, %ax
; X86-NEXT: setns %cl
; X86-NEXT: addl $32767, %ecx # imm = 0x7FFF
; X86-NEXT: subw %dx, %ax
; X86-NEXT: cmovol %ecx, %eax
; X86-NEXT: # kill: def $ax killed $ax killed $eax
; X86-NEXT: retl
;
; X64-LABEL: func16:
; X64: # %bb.0:
; X64-NEXT: imull %edx, %esi
; X64-NEXT: xorl %eax, %eax
; X64-NEXT: cmpw %si, %di
; X64-NEXT: setns %al
; X64-NEXT: addl $32767, %eax # imm = 0x7FFF
; X64-NEXT: subw %si, %di
; X64-NEXT: cmovnol %edi, %eax
; X64-NEXT: # kill: def $ax killed $ax killed $eax
; X64-NEXT: retq
%a = mul i16 %y, %z
%tmp = call i16 @llvm.ssub.sat.i16(i16 %x, i16 %a)
ret i16 %tmp
}
define signext i8 @func8(i8 signext %x, i8 signext %y, i8 signext %z) nounwind {
; X86-LABEL: func8:
; X86: # %bb.0:
; X86-NEXT: movb {{[0-9]+}}(%esp), %dl
; X86-NEXT: movb {{[0-9]+}}(%esp), %al
; X86-NEXT: mulb {{[0-9]+}}(%esp)
; X86-NEXT: xorl %ecx, %ecx
; X86-NEXT: cmpb %al, %dl
; X86-NEXT: setns %cl
; X86-NEXT: addl $127, %ecx
; X86-NEXT: subb %al, %dl
; X86-NEXT: movzbl %dl, %eax
; X86-NEXT: cmovol %ecx, %eax
; X86-NEXT: # kill: def $al killed $al killed $eax
; X86-NEXT: retl
;
; X64-LABEL: func8:
; X64: # %bb.0:
; X64-NEXT: movl %esi, %eax
; X64-NEXT: # kill: def $al killed $al killed $eax
; X64-NEXT: mulb %dl
; X64-NEXT: xorl %ecx, %ecx
; X64-NEXT: cmpb %al, %dil
; X64-NEXT: setns %cl
; X64-NEXT: addl $127, %ecx
; X64-NEXT: subb %al, %dil
; X64-NEXT: movzbl %dil, %eax
; X64-NEXT: cmovol %ecx, %eax
; X64-NEXT: # kill: def $al killed $al killed $eax
; X64-NEXT: retq
%a = mul i8 %y, %z
%tmp = call i8 @llvm.ssub.sat.i8(i8 %x, i8 %a)
ret i8 %tmp
}
define signext i4 @func4(i4 signext %x, i4 signext %y, i4 signext %z) nounwind {
; X86-LABEL: func4:
; X86: # %bb.0:
; X86-NEXT: movb {{[0-9]+}}(%esp), %cl
; X86-NEXT: movb {{[0-9]+}}(%esp), %al
; X86-NEXT: mulb {{[0-9]+}}(%esp)
; X86-NEXT: shlb $4, %al
; X86-NEXT: sarb $4, %al
; X86-NEXT: subb %al, %cl
; X86-NEXT: movzbl %cl, %eax
; X86-NEXT: cmpb $7, %cl
; X86-NEXT: movl $7, %ecx
; X86-NEXT: cmovll %eax, %ecx
; X86-NEXT: cmpb $-7, %cl
; X86-NEXT: movl $248, %eax
; X86-NEXT: cmovgel %ecx, %eax
; X86-NEXT: movsbl %al, %eax
; X86-NEXT: retl
;
; X64-LABEL: func4:
; X64: # %bb.0:
; X64-NEXT: movl %esi, %eax
; X64-NEXT: # kill: def $al killed $al killed $eax
; X64-NEXT: mulb %dl
; X64-NEXT: shlb $4, %al
; X64-NEXT: sarb $4, %al
; X64-NEXT: subb %al, %dil
; X64-NEXT: movzbl %dil, %eax
; X64-NEXT: cmpb $7, %al
; X64-NEXT: movl $7, %ecx
; X64-NEXT: cmovll %eax, %ecx
; X64-NEXT: cmpb $-7, %cl
; X64-NEXT: movl $248, %eax
; X64-NEXT: cmovgel %ecx, %eax
; X64-NEXT: movsbl %al, %eax
; X64-NEXT: retq
%a = mul i4 %y, %z
%tmp = call i4 @llvm.ssub.sat.i4(i4 %x, i4 %a)
ret i4 %tmp
}
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