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f3295eafa5
propagating one of the values it simplified to a constant across
a myriad of instructions. Notably, ptrtoint instructions when we had
a constant pointer (say, 0) didn't propagate that, blocking a massive
number of down-stream optimizations.
This was uncovered when investigating why we fail to inline and delete
the boilerplate in:
void f() {
std::vector<int> v;
v.push_back(1);
}
It turns out most of the efforts I've made thus far to improve the
analysis weren't making it far purely because of this. After this is
fixed, the store-to-load forwarding patch enables LLVM to optimize the
above to an empty function. We still can't nuke a second push_back, but
for different reasons.
There is a very real chance this will cause somewhat noticable changes
in inlining behavior, so please let me know if you see regressions (or
improvements!) because of this patch.
llvm-svn: 171196
251 lines
5.9 KiB
LLVM
251 lines
5.9 KiB
LLVM
; RUN: opt < %s -inline -inline-threshold=20 -S | FileCheck %s
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define internal i32 @callee1(i32 %A, i32 %B) {
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%C = sdiv i32 %A, %B
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ret i32 %C
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}
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define i32 @caller1() {
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; CHECK: define i32 @caller1
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; CHECK-NEXT: ret i32 3
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%X = call i32 @callee1( i32 10, i32 3 )
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ret i32 %X
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}
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define i32 @caller2() {
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; Check that we can constant-prop through instructions after inlining callee21
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; to get constants in the inlined callsite to callee22.
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; FIXME: Currently, the threshold is fixed at 20 because we don't perform
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; *recursive* cost analysis to realize that the nested call site will definitely
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; inline and be cheap. We should eventually do that and lower the threshold here
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; to 1.
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;
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; CHECK: @caller2
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; CHECK-NOT: call void @callee2
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; CHECK: ret
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%x = call i32 @callee21(i32 42, i32 48)
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ret i32 %x
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}
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define i32 @callee21(i32 %x, i32 %y) {
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%sub = sub i32 %y, %x
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%result = call i32 @callee22(i32 %sub)
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ret i32 %result
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}
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declare i8* @getptr()
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define i32 @callee22(i32 %x) {
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%icmp = icmp ugt i32 %x, 42
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br i1 %icmp, label %bb.true, label %bb.false
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bb.true:
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; This block musn't be counted in the inline cost.
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%x1 = add i32 %x, 1
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%x2 = add i32 %x1, 1
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%x3 = add i32 %x2, 1
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%x4 = add i32 %x3, 1
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%x5 = add i32 %x4, 1
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%x6 = add i32 %x5, 1
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%x7 = add i32 %x6, 1
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%x8 = add i32 %x7, 1
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ret i32 %x8
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bb.false:
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ret i32 %x
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}
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define i32 @caller3() {
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; Check that even if the expensive path is hidden behind several basic blocks,
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; it doesn't count toward the inline cost when constant-prop proves those paths
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; dead.
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;
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; CHECK: @caller3
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; CHECK-NOT: call
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; CHECK: ret i32 6
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entry:
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%x = call i32 @callee3(i32 42, i32 48)
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ret i32 %x
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}
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define i32 @callee3(i32 %x, i32 %y) {
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%sub = sub i32 %y, %x
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%icmp = icmp ugt i32 %sub, 42
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br i1 %icmp, label %bb.true, label %bb.false
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bb.true:
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%icmp2 = icmp ult i32 %sub, 64
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br i1 %icmp2, label %bb.true.true, label %bb.true.false
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bb.true.true:
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; This block musn't be counted in the inline cost.
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%x1 = add i32 %x, 1
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%x2 = add i32 %x1, 1
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%x3 = add i32 %x2, 1
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%x4 = add i32 %x3, 1
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%x5 = add i32 %x4, 1
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%x6 = add i32 %x5, 1
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%x7 = add i32 %x6, 1
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%x8 = add i32 %x7, 1
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br label %bb.merge
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bb.true.false:
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; This block musn't be counted in the inline cost.
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%y1 = add i32 %y, 1
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%y2 = add i32 %y1, 1
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%y3 = add i32 %y2, 1
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%y4 = add i32 %y3, 1
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%y5 = add i32 %y4, 1
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%y6 = add i32 %y5, 1
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%y7 = add i32 %y6, 1
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%y8 = add i32 %y7, 1
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br label %bb.merge
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bb.merge:
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%result = phi i32 [ %x8, %bb.true.true ], [ %y8, %bb.true.false ]
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ret i32 %result
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bb.false:
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ret i32 %sub
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}
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declare {i8, i1} @llvm.uadd.with.overflow.i8(i8 %a, i8 %b)
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define i8 @caller4(i8 %z) {
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; Check that we can constant fold through intrinsics such as the
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; overflow-detecting arithmetic instrinsics. These are particularly important
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; as they are used heavily in standard library code and generic C++ code where
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; the arguments are oftent constant but complete generality is required.
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;
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; CHECK: @caller4
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; CHECK-NOT: call
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; CHECK: ret i8 -1
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entry:
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%x = call i8 @callee4(i8 254, i8 14, i8 %z)
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ret i8 %x
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}
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define i8 @callee4(i8 %x, i8 %y, i8 %z) {
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%uadd = call {i8, i1} @llvm.uadd.with.overflow.i8(i8 %x, i8 %y)
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%o = extractvalue {i8, i1} %uadd, 1
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br i1 %o, label %bb.true, label %bb.false
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bb.true:
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ret i8 -1
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bb.false:
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; This block musn't be counted in the inline cost.
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%z1 = add i8 %z, 1
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%z2 = add i8 %z1, 1
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%z3 = add i8 %z2, 1
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%z4 = add i8 %z3, 1
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%z5 = add i8 %z4, 1
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%z6 = add i8 %z5, 1
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%z7 = add i8 %z6, 1
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%z8 = add i8 %z7, 1
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ret i8 %z8
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}
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define i64 @caller5(i64 %y) {
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; Check that we can round trip constants through various kinds of casts etc w/o
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; losing track of the constant prop in the inline cost analysis.
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;
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; CHECK: @caller5
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; CHECK-NOT: call
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; CHECK: ret i64 -1
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entry:
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%x = call i64 @callee5(i64 42, i64 %y)
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ret i64 %x
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}
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define i64 @callee5(i64 %x, i64 %y) {
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%inttoptr = inttoptr i64 %x to i8*
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%bitcast = bitcast i8* %inttoptr to i32*
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%ptrtoint = ptrtoint i32* %bitcast to i64
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%trunc = trunc i64 %ptrtoint to i32
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%zext = zext i32 %trunc to i64
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%cmp = icmp eq i64 %zext, 42
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br i1 %cmp, label %bb.true, label %bb.false
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bb.true:
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ret i64 -1
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bb.false:
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; This block musn't be counted in the inline cost.
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%y1 = add i64 %y, 1
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%y2 = add i64 %y1, 1
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%y3 = add i64 %y2, 1
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%y4 = add i64 %y3, 1
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%y5 = add i64 %y4, 1
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%y6 = add i64 %y5, 1
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%y7 = add i64 %y6, 1
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%y8 = add i64 %y7, 1
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ret i64 %y8
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}
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define i32 @PR13412.main() {
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; This is a somewhat complicated three layer subprogram that was reported to
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; compute the wrong value for a branch due to assuming that an argument
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; mid-inline couldn't be equal to another pointer.
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;
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; After inlining, the branch should point directly to the exit block, not to
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; the intermediate block.
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; CHECK: @PR13412.main
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; CHECK: br i1 true, label %[[TRUE_DEST:.*]], label %[[FALSE_DEST:.*]]
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; CHECK: [[FALSE_DEST]]:
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; CHECK-NEXT: call void @PR13412.fail()
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; CHECK: [[TRUE_DEST]]:
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; CHECK-NEXT: ret i32 0
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entry:
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%i1 = alloca i64
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store i64 0, i64* %i1
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%arraydecay = bitcast i64* %i1 to i32*
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%call = call i1 @PR13412.first(i32* %arraydecay, i32* %arraydecay)
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br i1 %call, label %cond.end, label %cond.false
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cond.false:
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call void @PR13412.fail()
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br label %cond.end
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cond.end:
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ret i32 0
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}
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define internal i1 @PR13412.first(i32* %a, i32* %b) {
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entry:
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%call = call i32* @PR13412.second(i32* %a, i32* %b)
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%cmp = icmp eq i32* %call, %b
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ret i1 %cmp
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}
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declare void @PR13412.fail()
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define internal i32* @PR13412.second(i32* %a, i32* %b) {
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entry:
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%sub.ptr.lhs.cast = ptrtoint i32* %b to i64
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%sub.ptr.rhs.cast = ptrtoint i32* %a to i64
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%sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
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%sub.ptr.div = ashr exact i64 %sub.ptr.sub, 2
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%cmp = icmp ugt i64 %sub.ptr.div, 1
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br i1 %cmp, label %if.then, label %if.end3
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if.then:
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%0 = load i32* %a
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%1 = load i32* %b
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%cmp1 = icmp eq i32 %0, %1
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br i1 %cmp1, label %return, label %if.end3
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if.end3:
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br label %return
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return:
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%retval.0 = phi i32* [ %b, %if.end3 ], [ %a, %if.then ]
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ret i32* %retval.0
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}
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