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fold comparisons of gep'd alloca points with null to false,

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implementing PR12013.  We now compile the testcase to:

__Z4testv:                              ## @_Z4testv
## BB#0:                                ## %_ZN4llvm15SmallVectorImplIiE9push_backERKi.exit
	pushq	%rbx
	subq	$64, %rsp
	leaq	32(%rsp), %rbx
	movq	%rbx, (%rsp)
	leaq	64(%rsp), %rax
	movq	%rax, 16(%rsp)
	movl	$1, 32(%rsp)
	leaq	36(%rsp), %rax
	movq	%rax, 8(%rsp)
	leaq	(%rsp), %rdi
	callq	__Z1gRN4llvm11SmallVectorIiLj8EEE
	movq	(%rsp), %rdi
	cmpq	%rbx, %rdi
	je	LBB0_2
## BB#1:
	callq	_free
LBB0_2:                                 ## %_ZN4llvm11SmallVectorIiLj8EED1Ev.exit
	addq	$64, %rsp
	popq	%rbx
	ret

instead of:

__Z4testv:                              ## @_Z4testv
## BB#0:
	pushq	%rbx
	subq	$64, %rsp
	xorl	%eax, %eax
	leaq	(%rsp), %rbx
	addq	$32, %rbx
	movq	%rbx, (%rsp)
	movq	%rbx, 8(%rsp)
	leaq	64(%rsp), %rcx
	movq	%rcx, 16(%rsp)
	je	LBB0_2
## BB#1:
	movl	$1, 32(%rsp)
	movq	%rbx, %rax
LBB0_2:                                 ## %_ZN4llvm15SmallVectorImplIiE9push_backERKi.exit
	addq	$4, %rax
	movq	%rax, 8(%rsp)
	leaq	(%rsp), %rdi
	callq	__Z1gRN4llvm11SmallVectorIiLj8EEE
	movq	(%rsp), %rdi
	cmpq	%rbx, %rdi
	je	LBB0_4
## BB#3:
	callq	_free
LBB0_4:                                 ## %_ZN4llvm11SmallVectorIiLj8EED1Ev.exit
	addq	$64, %rsp
	popq	%rbx
	ret

This doesn't shrink clang noticably though.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150944 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2012-02-20 00:42:49 +00:00
parent 637f949a7f
commit b053fc1c92
2 changed files with 33 additions and 5 deletions
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13
test/Transforms/InstSimplify/compare.ll
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@@ -446,9 +446,20 @@ define <2 x i1> @vectorselect1(<2 x i1> %cond) {
; CHECK: ret <2 x i1> %cond
}
define <2 x i1> @vectorselectcrash(i32 %arg1) { ; PR11948
; PR11948
define <2 x i1> @vectorselectcrash(i32 %arg1) {
%tobool40 = icmp ne i32 %arg1, 0
%cond43 = select i1 %tobool40, <2 x i16> <i16 -5, i16 66>, <2 x i16> <i16 46, i16 1>
%cmp45 = icmp ugt <2 x i16> %cond43, <i16 73, i16 21>
ret <2 x i1> %cmp45
}
; PR12013
define i1 @alloca_compare(i64 %idx) {
%sv = alloca { i32, i32, [124 x i32] }
%1 = getelementptr inbounds { i32, i32, [124 x i32] }* %sv, i32 0, i32 2, i64 %idx
%2 = icmp eq i32* %1, null
ret i1 %2
; CHECK: alloca_compare
; CHECK: ret i1 false
}