llvm/test/Transforms/GlobalOpt/2009-03-07-PromotePtrToBool.ll
Chris Lattner 6f6923fd4f fix a serious pessimization that Tron on IRC pointed out where we would
"boolify" pointers, generating really awful code because getting the pointer
value requires a load itself.  Before:

_foo:
	movb	$1, _X.b
	ret
_get:
	xorl	%ecx, %ecx
	movb	_X.b, %al
	testb	%al, %al
	movl	$_Y, %eax
	cmove	%ecx, %eax
	ret

With the xform disabled:

_foo:
	movl	$_Y, _X
	ret
_get:
	movl	_X, %eax
	ret



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66351 91177308-0d34-0410-b5e6-96231b3b80d8
2009-03-07 23:32:02 +00:00

18 lines
546 B
LLVM

; RUN: llvm-as < %s | opt -globalopt | llvm-dis | grep {@X = internal global i32}
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i386-apple-darwin7"
@X = internal global i32* null ; <i32**> [#uses=2]
@Y = internal global i32 0 ; <i32*> [#uses=1]
define void @foo() nounwind {
entry:
store i32* @Y, i32** @X, align 4
ret void
}
define i32* @get() nounwind {
entry:
%0 = load i32** @X, align 4 ; <i32*> [#uses=1]
ret i32* %0
}