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llvm-project/llvm/test/Analysis/BasicAA/gep-alias.ll

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Change the other half of aliasGEP (which handles GEP differencing) to use DecomposeGEPExpression. This dramatically simplifies and shrinks the code by eliminating the horrible CheckGEPInstructions method, fixes a miscompilation (@test3) and makes the code more aggressive. In particular, we now handle the @test4 case, which is reduced from the SmallPtrSet constructor. Missing this caused us to emit a variable length memset instead of a fixed size one. llvm-svn: 89922
2009-11-26 10:17:34 +08:00
; RUN: opt < %s -gvn -instcombine -S |& FileCheck %s
Allow basicaa to walk through geps with identical indices in parallel, allowing it to decide that P/Q must alias if A/B must alias in things like: P = gep A, 0, i, 1 Q = gep B, 0, i, 1 This allows GVN to delete 62 more instructions out of 403.gcc. llvm-svn: 60820
2008-12-10 09:04:47 +08:00
; Make sure that basicaa thinks R and r are must aliases.
Change the other half of aliasGEP (which handles GEP differencing) to use DecomposeGEPExpression. This dramatically simplifies and shrinks the code by eliminating the horrible CheckGEPInstructions method, fixes a miscompilation (@test3) and makes the code more aggressive. In particular, we now handle the @test4 case, which is reduced from the SmallPtrSet constructor. Missing this caused us to emit a variable length memset instead of a fixed size one. llvm-svn: 89922
2009-11-26 10:17:34 +08:00
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"
define i32 @test1(i8 * %P) {
Allow basicaa to walk through geps with identical indices in parallel, allowing it to decide that P/Q must alias if A/B must alias in things like: P = gep A, 0, i, 1 Q = gep B, 0, i, 1 This allows GVN to delete 62 more instructions out of 403.gcc. llvm-svn: 60820
2008-12-10 09:04:47 +08:00
entry:
%Q = bitcast i8* %P to {i32, i32}*
%R = getelementptr {i32, i32}* %Q, i32 0, i32 1
%S = load i32* %R
%q = bitcast i8* %P to {i32, i32}*
%r = getelementptr {i32, i32}* %q, i32 0, i32 1
%s = load i32* %r
%t = sub i32 %S, %s
ret i32 %t
Change the other half of aliasGEP (which handles GEP differencing) to use DecomposeGEPExpression. This dramatically simplifies and shrinks the code by eliminating the horrible CheckGEPInstructions method, fixes a miscompilation (@test3) and makes the code more aggressive. In particular, we now handle the @test4 case, which is reduced from the SmallPtrSet constructor. Missing this caused us to emit a variable length memset instead of a fixed size one. llvm-svn: 89922
2009-11-26 10:17:34 +08:00
; CHECK: @test1
; CHECK: ret i32 0
}
define i32 @test2(i8 * %P) {
entry:
%Q = bitcast i8* %P to {i32, i32, i32}*
%R = getelementptr {i32, i32, i32}* %Q, i32 0, i32 1
%S = load i32* %R
%r = getelementptr {i32, i32, i32}* %Q, i32 0, i32 2
store i32 42, i32* %r
%s = load i32* %R
%t = sub i32 %S, %s
ret i32 %t
; CHECK: @test2
; CHECK: ret i32 0
}
; This was a miscompilation.
define i32 @test3({float, {i32, i32, i32}}* %P) {
entry:
%P2 = getelementptr {float, {i32, i32, i32}}* %P, i32 0, i32 1
%R = getelementptr {i32, i32, i32}* %P2, i32 0, i32 1
%S = load i32* %R
%r = getelementptr {i32, i32, i32}* %P2, i32 0, i32 2
store i32 42, i32* %r
%s = load i32* %R
%t = sub i32 %S, %s
ret i32 %t
; CHECK: @test3
; CHECK: ret i32 0
}
;; This is reduced from the SmallPtrSet constructor.
%SmallPtrSetImpl = type { i8**, i32, i32, i32, [1 x i8*] }
%SmallPtrSet64 = type { %SmallPtrSetImpl, [64 x i8*] }
define i32 @test4(%SmallPtrSet64* %P) {
entry:
%tmp2 = getelementptr inbounds %SmallPtrSet64* %P, i64 0, i32 0, i32 1
store i32 64, i32* %tmp2, align 8
%tmp3 = getelementptr inbounds %SmallPtrSet64* %P, i64 0, i32 0, i32 4, i64 64
store i8* null, i8** %tmp3, align 8
%tmp4 = load i32* %tmp2, align 8
ret i32 %tmp4
; CHECK: @test4
; CHECK: ret i32 64
Allow basicaa to walk through geps with identical indices in parallel, allowing it to decide that P/Q must alias if A/B must alias in things like: P = gep A, 0, i, 1 Q = gep B, 0, i, 1 This allows GVN to delete 62 more instructions out of 403.gcc. llvm-svn: 60820
2008-12-10 09:04:47 +08:00
}
teach basicaa that A[i] != A[i+1]. llvm-svn: 89951
2009-11-27 00:18:10 +08:00
; P[i] != p[i+1]
define i32 @test5(i32* %p, i64 %i) {
%pi = getelementptr i32* %p, i64 %i
%i.next = add 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: @test5
; CHECK: ret i32 0
}
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 llvm-svn: 89952
2009-11-27 00:26:43 +08:00
; 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
}
teach basicaa that A[i] != A[i+1]. llvm-svn: 89951
2009-11-27 00:18:10 +08:00