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llvm-mirror/test/CodeGen/X86/not-of-dec.ll
Roman Lebedev f9c10b284e [DAGCombiner] ~(add X, -1) -> neg X fold
The fold 'A - (A & (B - 1))' -> 'A & (0 - B)'
added in 8dab0a4a7d691f2704f1079538e0ef29548db159
is too specific. It should just be 'A - (A & B)' -> 'A & (~B)',
but we currently fail to sink that '~' into `(B - 1)`.

Name: ~(X - 1)  ->  (0 - X)
%o = add i32 %X, -1
%r = xor i32 %o, -1
  =>
%r = sub i32 0, %X

https://rise4fun.com/Alive/rjU
2020-01-03 17:55:46 +03:00

118 lines
3.1 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=i686-unknown-linux-gnu < %s | FileCheck %s --check-prefixes=CHECK,X86
; RUN: llc -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s --check-prefixes=CHECK,X64
; Fold
; ~(X - 1)
; To
; - X
;
; This needs to be a backend-level fold because only by now pointers
; are just registers; in middle-end IR this can only be done via @llvm.ptrmask()
; intrinsic which is not sufficiently widely-spread yet.
;
; https://bugs.llvm.org/show_bug.cgi?id=44448
; The basic positive tests
define i32 @t0_32(i32 %alignment) nounwind {
; X86-LABEL: t0_32:
; X86: # %bb.0:
; X86-NEXT: xorl %eax, %eax
; X86-NEXT: subl {{[0-9]+}}(%esp), %eax
; X86-NEXT: retl
;
; X64-LABEL: t0_32:
; X64: # %bb.0:
; X64-NEXT: movl %edi, %eax
; X64-NEXT: negl %eax
; X64-NEXT: retq
%mask = add i32 %alignment, -1
%invmask = xor i32 %mask, -1
ret i32 %invmask
}
define i64 @t1_64(i64 %alignment) nounwind {
; X86-LABEL: t1_64:
; X86: # %bb.0:
; X86-NEXT: xorl %edx, %edx
; X86-NEXT: xorl %eax, %eax
; X86-NEXT: subl {{[0-9]+}}(%esp), %eax
; X86-NEXT: sbbl {{[0-9]+}}(%esp), %edx
; X86-NEXT: retl
;
; X64-LABEL: t1_64:
; X64: # %bb.0:
; X64-NEXT: movq %rdi, %rax
; X64-NEXT: negq %rax
; X64-NEXT: retq
%mask = add i64 %alignment, -1
%invmask = xor i64 %mask, -1
ret i64 %invmask
}
; Extra use test
define i32 @t2_extrause(i32 %alignment, i32* %mask_storage) nounwind {
; X86-LABEL: t2_extrause:
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
; X86-NEXT: leal -1(%eax), %edx
; X86-NEXT: movl %edx, (%ecx)
; X86-NEXT: negl %eax
; X86-NEXT: retl
;
; X64-LABEL: t2_extrause:
; X64: # %bb.0:
; X64-NEXT: movl %edi, %eax
; X64-NEXT: leal -1(%rax), %ecx
; X64-NEXT: movl %ecx, (%rsi)
; X64-NEXT: negl %eax
; X64-NEXT: # kill: def $eax killed $eax killed $rax
; X64-NEXT: retq
%mask = add i32 %alignment, -1
store i32 %mask, i32* %mask_storage
%invmask = xor i32 %mask, -1
ret i32 %invmask
}
; Negative tests
define i32 @n3_not_dec(i32 %alignment) nounwind {
; X86-LABEL: n3_not_dec:
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
; X86-NEXT: incl %eax
; X86-NEXT: notl %eax
; X86-NEXT: retl
;
; X64-LABEL: n3_not_dec:
; X64: # %bb.0:
; X64-NEXT: # kill: def $edi killed $edi def $rdi
; X64-NEXT: leal 1(%rdi), %eax
; X64-NEXT: notl %eax
; X64-NEXT: retq
%mask = add i32 %alignment, 1 ; not -1
%invmask = xor i32 %mask, -1
ret i32 %invmask
}
define i32 @n4_not_not(i32 %alignment) nounwind {
; X86-LABEL: n4_not_not:
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
; X86-NEXT: decl %eax
; X86-NEXT: xorl $1, %eax
; X86-NEXT: retl
;
; X64-LABEL: n4_not_not:
; X64: # %bb.0:
; X64-NEXT: # kill: def $edi killed $edi def $rdi
; X64-NEXT: leal -1(%rdi), %eax
; X64-NEXT: xorl $1, %eax
; X64-NEXT: retq
%mask = add i32 %alignment, -1
%invmask = xor i32 %mask, 1 ; not -1
ret i32 %invmask
}