llvm-6502/test/CodeGen/X86/add.ll
Benjamin Kramer f50125ecaa DAGCombine add (sext i1), X into sub X, (zext i1) if sext from i1 is illegal. The latter usually compiles into smaller code.
example code:
unsigned foo(unsigned x, unsigned y) {
  if (x != 0) y--;
  return y;
}

before:
  _foo:                           ## @foo
    cmpl  $1, 4(%esp)             ## encoding: [0x83,0x7c,0x24,0x04,0x01]
    sbbl  %eax, %eax              ## encoding: [0x19,0xc0]
    notl  %eax                    ## encoding: [0xf7,0xd0]
    addl  8(%esp), %eax           ## encoding: [0x03,0x44,0x24,0x08]
    ret                           ## encoding: [0xc3]

after:
  _foo:                           ## @foo
    cmpl  $1, 4(%esp)             ## encoding: [0x83,0x7c,0x24,0x04,0x01]
    movl  8(%esp), %eax           ## encoding: [0x8b,0x44,0x24,0x08]
    adcl  $-1, %eax               ## encoding: [0x83,0xd0,0xff]
    ret                           ## encoding: [0xc3]



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122455 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-22 23:17:45 +00:00

135 lines
3.0 KiB
LLVM

; RUN: llc < %s -march=x86 | FileCheck %s -check-prefix=X32
; RUN: llc < %s -march=x86-64 | FileCheck %s -check-prefix=X64
; The immediate can be encoded in a smaller way if the
; instruction is a sub instead of an add.
define i32 @test1(i32 inreg %a) nounwind {
%b = add i32 %a, 128
ret i32 %b
; X32: subl $-128, %eax
; X64: subl $-128,
}
define i64 @test2(i64 inreg %a) nounwind {
%b = add i64 %a, 2147483648
ret i64 %b
; X32: addl $-2147483648, %eax
; X64: subq $-2147483648,
}
define i64 @test3(i64 inreg %a) nounwind {
%b = add i64 %a, 128
ret i64 %b
; X32: addl $128, %eax
; X64: subq $-128,
}
define i1 @test4(i32 %v1, i32 %v2, i32* %X) nounwind {
entry:
%t = call {i32, i1} @llvm.sadd.with.overflow.i32(i32 %v1, i32 %v2)
%sum = extractvalue {i32, i1} %t, 0
%obit = extractvalue {i32, i1} %t, 1
br i1 %obit, label %overflow, label %normal
normal:
store i32 0, i32* %X
br label %overflow
overflow:
ret i1 false
; X32: test4:
; X32: addl
; X32-NEXT: jo
; X64: test4:
; X64: addl %esi, %edi
; X64-NEXT: jo
}
define i1 @test5(i32 %v1, i32 %v2, i32* %X) nounwind {
entry:
%t = call {i32, i1} @llvm.uadd.with.overflow.i32(i32 %v1, i32 %v2)
%sum = extractvalue {i32, i1} %t, 0
%obit = extractvalue {i32, i1} %t, 1
br i1 %obit, label %carry, label %normal
normal:
store i32 0, i32* %X
br label %carry
carry:
ret i1 false
; X32: test5:
; X32: addl
; X32-NEXT: jb
; X64: test5:
; X64: addl %esi, %edi
; X64-NEXT: jb
}
declare {i32, i1} @llvm.sadd.with.overflow.i32(i32, i32)
declare {i32, i1} @llvm.uadd.with.overflow.i32(i32, i32)
define i64 @test6(i64 %A, i32 %B) nounwind {
%tmp12 = zext i32 %B to i64 ; <i64> [#uses=1]
%tmp3 = shl i64 %tmp12, 32 ; <i64> [#uses=1]
%tmp5 = add i64 %tmp3, %A ; <i64> [#uses=1]
ret i64 %tmp5
; X32: test6:
; X32: movl 12(%esp), %edx
; X32-NEXT: addl 8(%esp), %edx
; X32-NEXT: movl 4(%esp), %eax
; X32-NEXT: ret
; X64: test6:
; X64: shlq $32, %rsi
; X64: leaq (%rsi,%rdi), %rax
; X64: ret
}
define {i32, i1} @test7(i32 %v1, i32 %v2) nounwind {
%t = call {i32, i1} @llvm.uadd.with.overflow.i32(i32 %v1, i32 %v2)
ret {i32, i1} %t
}
; X64: test7:
; X64: addl %esi, %eax
; X64-NEXT: setb %dl
; X64-NEXT: ret
; PR5443
define {i64, i1} @test8(i64 %left, i64 %right) nounwind {
entry:
%extleft = zext i64 %left to i65
%extright = zext i64 %right to i65
%sum = add i65 %extleft, %extright
%res.0 = trunc i65 %sum to i64
%overflow = and i65 %sum, -18446744073709551616
%res.1 = icmp ne i65 %overflow, 0
%final0 = insertvalue {i64, i1} undef, i64 %res.0, 0
%final1 = insertvalue {i64, i1} %final0, i1 %res.1, 1
ret {i64, i1} %final1
}
; X64: test8:
; X64: addq
; X64-NEXT: sbbq
; X64-NEXT: testb
define i32 @test9(i32 %x, i32 %y) nounwind readnone {
%cmp = icmp eq i32 %x, 10
%sub = sext i1 %cmp to i32
%cond = add i32 %sub, %y
ret i32 %cond
; X64: test9:
; X64: cmpl $10
; X64: sete
; X64: subl
; X64: ret
}