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llvm-mirror/test/Transforms/InstCombine/load.ll
Chandler Carruth 69ab5e9da0 Fix a miscompile introduced in r220178.
The original code had an implicit assumption that if the test for
allocas or globals was reached, the two pointers were not equal. With my
changes to make the pointer analysis more powerful here, I also had to
guard against circumstances where the results weren't useful. That in
turn violated the assumption and gave rise to a circumstance in which we
could have a store with both the queried pointer and stored pointer
rooted at *the same* alloca. Clearly, we cannot ignore such a store.
There are other things we might do in this code to better handle the
case of both pointers ending up at the same alloca or global, but it
seems best to at least make the test explicit in what it intends to
check.

I've added tests for both the alloca and global case here.

llvm-svn: 220190
2014-10-20 10:03:01 +00:00

153 lines
3.9 KiB
LLVM

; RUN: opt -instcombine -S < %s | FileCheck %s
; This test makes sure that these instructions are properly eliminated.
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
@X = constant i32 42 ; <i32*> [#uses=2]
@X2 = constant i32 47 ; <i32*> [#uses=1]
@Y = constant [2 x { i32, float }] [ { i32, float } { i32 12, float 1.000000e+00 }, { i32, float } { i32 37, float 0x3FF3B2FEC0000000 } ] ; <[2 x { i32, float }]*> [#uses=2]
@Z = constant [2 x { i32, float }] zeroinitializer ; <[2 x { i32, float }]*> [#uses=1]
@GLOBAL = internal constant [4 x i32] zeroinitializer
; CHECK-LABEL: @test1(
; CHECK-NOT: load
define i32 @test1() {
%B = load i32* @X ; <i32> [#uses=1]
ret i32 %B
}
; CHECK-LABEL: @test2(
; CHECK-NOT: load
define float @test2() {
%A = getelementptr [2 x { i32, float }]* @Y, i64 0, i64 1, i32 1 ; <float*> [#uses=1]
%B = load float* %A ; <float> [#uses=1]
ret float %B
}
; CHECK-LABEL: @test3(
; CHECK-NOT: load
define i32 @test3() {
%A = getelementptr [2 x { i32, float }]* @Y, i64 0, i64 0, i32 0 ; <i32*> [#uses=1]
%B = load i32* %A ; <i32> [#uses=1]
ret i32 %B
}
; CHECK-LABEL: @test4(
; CHECK-NOT: load
define i32 @test4() {
%A = getelementptr [2 x { i32, float }]* @Z, i64 0, i64 1, i32 0 ; <i32*> [#uses=1]
%B = load i32* %A ; <i32> [#uses=1]
ret i32 %B
}
; CHECK-LABEL: @test5(
; CHECK-NOT: load
define i32 @test5(i1 %C) {
%Y = select i1 %C, i32* @X, i32* @X2 ; <i32*> [#uses=1]
%Z = load i32* %Y ; <i32> [#uses=1]
ret i32 %Z
}
; CHECK-LABEL: @test7(
; CHECK-NOT: load
define i32 @test7(i32 %X) {
%V = getelementptr i32* null, i32 %X ; <i32*> [#uses=1]
%R = load i32* %V ; <i32> [#uses=1]
ret i32 %R
}
; CHECK-LABEL: @test8(
; CHECK-NOT: load
define i32 @test8(i32* %P) {
store i32 1, i32* %P
%X = load i32* %P ; <i32> [#uses=1]
ret i32 %X
}
; CHECK-LABEL: @test9(
; CHECK-NOT: load
define i32 @test9(i32* %P) {
%X = load i32* %P ; <i32> [#uses=1]
%Y = load i32* %P ; <i32> [#uses=1]
%Z = sub i32 %X, %Y ; <i32> [#uses=1]
ret i32 %Z
}
; CHECK-LABEL: @test10(
; CHECK-NOT: load
define i32 @test10(i1 %C.upgrd.1, i32* %P, i32* %Q) {
br i1 %C.upgrd.1, label %T, label %F
T: ; preds = %0
store i32 1, i32* %Q
store i32 0, i32* %P
br label %C
F: ; preds = %0
store i32 0, i32* %P
br label %C
C: ; preds = %F, %T
%V = load i32* %P ; <i32> [#uses=1]
ret i32 %V
}
; CHECK-LABEL: @test11(
; CHECK-NOT: load
define double @test11(double* %p) {
%t0 = getelementptr double* %p, i32 1
store double 2.0, double* %t0
%t1 = getelementptr double* %p, i32 1
%x = load double* %t1
ret double %x
}
; CHECK-LABEL: @test12(
; CHECK-NOT: load
define i32 @test12(i32* %P) {
%A = alloca i32
store i32 123, i32* %A
; Cast the result of the load not the source
%Q = bitcast i32* %A to i32*
%V = load i32* %Q
ret i32 %V
}
; CHECK-LABEL: @test13(
; CHECK-NOT: load
define <16 x i8> @test13(<2 x i64> %x) {
%tmp = load <16 x i8>* bitcast ([4 x i32]* @GLOBAL to <16 x i8>*)
ret <16 x i8> %tmp
}
define i8 @test14(i8 %x, i32 %y) {
; This test must not have the store of %x forwarded to the load -- there is an
; intervening store if %y. However, the intervening store occurs with a different
; type and size and to a different pointer value. This is ensuring that none of
; those confuse the analysis into thinking that the second store does not alias
; the first.
; CHECK-LABEL: @test14(
; CHECK: %[[R:.*]] = load i8*
; CHECK-NEXT: ret i8 %[[R]]
%a = alloca i32
%a.i8 = bitcast i32* %a to i8*
store i8 %x, i8* %a.i8
store i32 %y, i32* %a
%r = load i8* %a.i8
ret i8 %r
}
@test15_global = external global i32
define i8 @test15(i8 %x, i32 %y) {
; Same test as @test14 essentially, but using a global instead of an alloca.
; CHECK-LABEL: @test15(
; CHECK: %[[R:.*]] = load i8*
; CHECK-NEXT: ret i8 %[[R]]
%g.i8 = bitcast i32* @test15_global to i8*
store i8 %x, i8* %g.i8
store i32 %y, i32* @test15_global
%r = load i8* %g.i8
ret i8 %r
}