llvm-6502/test/CodeGen/X86/isel-sink2.ll
Chris Lattner 2efbbb38ba Teach CodeGenPrepare to look through Bitcast instructions when attempting to
optimize addressing modes.  This allows us to optimize things like isel-sink2.ll
into:

	movl	4(%esp), %eax
	cmpb	$0, 4(%eax)
	jne	LBB1_2	## F
LBB1_1:	## TB
	movl	$4, %eax
	ret
LBB1_2:	## F
	movzbl	7(%eax), %eax
	ret

instead of:

_test:
	movl	4(%esp), %eax
	cmpb	$0, 4(%eax)
	leal	4(%eax), %eax
	jne	LBB1_2	## F
LBB1_1:	## TB
	movl	$4, %eax
	ret
LBB1_2:	## F
	movzbl	3(%eax), %eax
	ret

This shrinks (e.g.) 403.gcc from 1133510 to 1128345 lines of .s.

Note that the 2008-10-16-SpillerBug.ll testcase is dubious at best, I doubt
it is really testing what it thinks it is.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60068 91177308-0d34-0410-b5e6-96231b3b80d8
2008-11-26 00:26:16 +00:00

17 lines
378 B
LLVM

; RUN: llvm-as < %s | llc -march=x86 | grep {movzbl.7(%...)}
; RUN: llvm-as < %s | llc -march=x86 | not grep leal
define i8 @test(i32 *%P) nounwind {
%Q = getelementptr i32* %P, i32 1
%R = bitcast i32* %Q to i8*
%S = load i8* %R
%T = icmp eq i8 %S, 0
br i1 %T, label %TB, label %F
TB:
ret i8 4
F:
%U = getelementptr i8* %R, i32 3
%V = load i8* %U
ret i8 %V
}