From 5d5261c819fa2a203dc8d09c7bb71e041a12cd69 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Thu, 26 Nov 2009 16:26:43 +0000 Subject: Teach basicaa that x|c == x+c when the c bits of x are clear. This allows us to compile the example in readme.txt into: LBB1_1: ## %bb movl 4(%rdx,%rax), %ecx movl %ecx, %esi imull (%rdx,%rax), %esi imull %esi, %ecx movl %esi, 8(%rdx,%rax) imull %ecx, %esi movl %ecx, 12(%rdx,%rax) movl %esi, 16(%rdx,%rax) imull %ecx, %esi movl %esi, 20(%rdx,%rax) addq $16, %rax cmpq $4000, %rax jne LBB1_1 instead of: LBB1_1: movl (%rdx,%rax), %ecx imull 4(%rdx,%rax), %ecx movl %ecx, 8(%rdx,%rax) imull 4(%rdx,%rax), %ecx movl %ecx, 12(%rdx,%rax) imull 8(%rdx,%rax), %ecx movl %ecx, 16(%rdx,%rax) imull 12(%rdx,%rax), %ecx movl %ecx, 20(%rdx,%rax) addq $16, %rax cmpq $4000, %rax jne LBB1_1 GCC (4.2) doesn't seem to be able to eliminate the loads in this testcase either, it generates: L2: movl (%rdx), %eax imull 4(%rdx), %eax movl %eax, 8(%rdx) imull 4(%rdx), %eax movl %eax, 12(%rdx) imull 8(%rdx), %eax movl %eax, 16(%rdx) imull 12(%rdx), %eax movl %eax, 20(%rdx) addl $4, %ecx addq $16, %rdx cmpl $1002, %ecx jne L2 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89952 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/Analysis/BasicAA/gep-alias.ll | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'test') diff --git a/test/Analysis/BasicAA/gep-alias.ll b/test/Analysis/BasicAA/gep-alias.ll index 0c5f7ac337..320c9907d5 100644 --- a/test/Analysis/BasicAA/gep-alias.ll +++ b/test/Analysis/BasicAA/gep-alias.ll @@ -86,4 +86,18 @@ define i32 @test5(i32* %p, i64 %i) { ; CHECK: ret i32 0 } +; P[i] != p[(i*4)|1] +define i32 @test6(i32* %p, i64 %i1) { + %i = shl i64 %i1, 2 + %pi = getelementptr i32* %p, i64 %i + %i.next = or i64 %i, 1 + %pi.next = getelementptr i32* %p, i64 %i.next + %x = load i32* %pi + store i32 42, i32* %pi.next + %y = load i32* %pi + %z = sub i32 %x, %y + ret i32 %z +; CHECK: @test6 +; CHECK: ret i32 0 +} -- cgit v1.2.3