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llvm-mirror/test/Transforms/SROA/phi-and-select.ll
Chandler Carruth 6e02238cee Teach the integer-promotion rewrite strategy to be endianness aware.
Sorry for this being broken so long. =/

As part of this, switch all of the existing tests to be Little Endian,
which is the behavior I was asserting in them anyways! Add in a new
big-endian test that checks the interesting behavior there.

Another part of this is to tighten the rules abotu when we perform the
full-integer promotion. This logic now rejects cases where there fully
promoted integer is a non-multiple-of-8 bitwidth or cases where the
loads or stores touch bits which are in the allocated space of the
alloca but are not loaded or stored when accessing the integer. Sadly,
these aren't really observable today as the rest of the pass will
already ensure the invariants hold. However, the latter situation is
likely to become a potential concern in the future.

Thanks to Benjamin and Duncan for early review of this patch. I'm still
looking into whether there are further endianness issues, please let me
know if anyone sees BE failures persisting past this.

llvm-svn: 165219
2012-10-04 10:39:28 +00:00

393 lines
9.2 KiB
LLVM

; RUN: opt < %s -sroa -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n8:16:32:64"
define i32 @test1() {
; CHECK: @test1
entry:
%a = alloca [2 x i32]
; CHECK-NOT: alloca
%a0 = getelementptr [2 x i32]* %a, i64 0, i32 0
%a1 = getelementptr [2 x i32]* %a, i64 0, i32 1
store i32 0, i32* %a0
store i32 1, i32* %a1
%v0 = load i32* %a0
%v1 = load i32* %a1
; CHECK-NOT: store
; CHECK-NOT: load
%cond = icmp sle i32 %v0, %v1
br i1 %cond, label %then, label %exit
then:
br label %exit
exit:
%phi = phi i32* [ %a1, %then ], [ %a0, %entry ]
; CHECK: phi i32 [ 1, %{{.*}} ], [ 0, %{{.*}} ]
%result = load i32* %phi
ret i32 %result
}
define i32 @test2() {
; CHECK: @test2
entry:
%a = alloca [2 x i32]
; CHECK-NOT: alloca
%a0 = getelementptr [2 x i32]* %a, i64 0, i32 0
%a1 = getelementptr [2 x i32]* %a, i64 0, i32 1
store i32 0, i32* %a0
store i32 1, i32* %a1
%v0 = load i32* %a0
%v1 = load i32* %a1
; CHECK-NOT: store
; CHECK-NOT: load
%cond = icmp sle i32 %v0, %v1
%select = select i1 %cond, i32* %a1, i32* %a0
; CHECK: select i1 %{{.*}}, i32 1, i32 0
%result = load i32* %select
ret i32 %result
}
define i32 @test3(i32 %x) {
; CHECK: @test3
entry:
%a = alloca [2 x i32]
; CHECK-NOT: alloca
; Note that we build redundant GEPs here to ensure that having different GEPs
; into the same alloca partation continues to work with PHI speculation. This
; was the underlying cause of PR13926.
%a0 = getelementptr [2 x i32]* %a, i64 0, i32 0
%a0b = getelementptr [2 x i32]* %a, i64 0, i32 0
%a1 = getelementptr [2 x i32]* %a, i64 0, i32 1
%a1b = getelementptr [2 x i32]* %a, i64 0, i32 1
store i32 0, i32* %a0
store i32 1, i32* %a1
; CHECK-NOT: store
switch i32 %x, label %bb0 [ i32 1, label %bb1
i32 2, label %bb2
i32 3, label %bb3
i32 4, label %bb4
i32 5, label %bb5
i32 6, label %bb6
i32 7, label %bb7 ]
bb0:
br label %exit
bb1:
br label %exit
bb2:
br label %exit
bb3:
br label %exit
bb4:
br label %exit
bb5:
br label %exit
bb6:
br label %exit
bb7:
br label %exit
exit:
%phi = phi i32* [ %a1, %bb0 ], [ %a0, %bb1 ], [ %a0, %bb2 ], [ %a1, %bb3 ],
[ %a1b, %bb4 ], [ %a0b, %bb5 ], [ %a0b, %bb6 ], [ %a1b, %bb7 ]
; CHECK: phi i32 [ 1, %{{.*}} ], [ 0, %{{.*}} ], [ 0, %{{.*}} ], [ 1, %{{.*}} ], [ 1, %{{.*}} ], [ 0, %{{.*}} ], [ 0, %{{.*}} ], [ 1, %{{.*}} ]
%result = load i32* %phi
ret i32 %result
}
define i32 @test4() {
; CHECK: @test4
entry:
%a = alloca [2 x i32]
; CHECK-NOT: alloca
%a0 = getelementptr [2 x i32]* %a, i64 0, i32 0
%a1 = getelementptr [2 x i32]* %a, i64 0, i32 1
store i32 0, i32* %a0
store i32 1, i32* %a1
%v0 = load i32* %a0
%v1 = load i32* %a1
; CHECK-NOT: store
; CHECK-NOT: load
%cond = icmp sle i32 %v0, %v1
%select = select i1 %cond, i32* %a0, i32* %a0
; CHECK-NOT: select
%result = load i32* %select
ret i32 %result
; CHECK: ret i32 0
}
define i32 @test5(i32* %b) {
; CHECK: @test5
entry:
%a = alloca [2 x i32]
; CHECK-NOT: alloca
%a1 = getelementptr [2 x i32]* %a, i64 0, i32 1
store i32 1, i32* %a1
; CHECK-NOT: store
%select = select i1 true, i32* %a1, i32* %b
; CHECK-NOT: select
%result = load i32* %select
; CHECK-NOT: load
ret i32 %result
; CHECK: ret i32 1
}
declare void @f(i32*, i32*)
define i32 @test6(i32* %b) {
; CHECK: @test6
entry:
%a = alloca [2 x i32]
%c = alloca i32
; CHECK-NOT: alloca
%a1 = getelementptr [2 x i32]* %a, i64 0, i32 1
store i32 1, i32* %a1
%select = select i1 true, i32* %a1, i32* %b
%select2 = select i1 false, i32* %a1, i32* %b
%select3 = select i1 false, i32* %c, i32* %b
; CHECK: %[[select2:.*]] = select i1 false, i32* undef, i32* %b
; CHECK: %[[select3:.*]] = select i1 false, i32* undef, i32* %b
; Note, this would potentially escape the alloca pointer except for the
; constant folding of the select.
call void @f(i32* %select2, i32* %select3)
; CHECK: call void @f(i32* %[[select2]], i32* %[[select3]])
%result = load i32* %select
; CHECK-NOT: load
%dead = load i32* %c
ret i32 %result
; CHECK: ret i32 1
}
define i32 @test7() {
; CHECK: @test7
; CHECK-NOT: alloca
entry:
%X = alloca i32
br i1 undef, label %good, label %bad
good:
%Y1 = getelementptr i32* %X, i64 0
store i32 0, i32* %Y1
br label %exit
bad:
%Y2 = getelementptr i32* %X, i64 1
store i32 0, i32* %Y2
br label %exit
exit:
%P = phi i32* [ %Y1, %good ], [ %Y2, %bad ]
; CHECK: %[[phi:.*]] = phi i32 [ 0, %good ],
%Z2 = load i32* %P
ret i32 %Z2
; CHECK: ret i32 %[[phi]]
}
define i32 @test8(i32 %b, i32* %ptr) {
; Ensure that we rewrite allocas to the used type when that use is hidden by
; a PHI that can be speculated.
; CHECK: @test8
; CHECK-NOT: alloca
; CHECK-NOT: load
; CHECK: %[[value:.*]] = load i32* %ptr
; CHECK-NOT: load
; CHECK: %[[result:.*]] = phi i32 [ undef, %else ], [ %[[value]], %then ]
; CHECK-NEXT: ret i32 %[[result]]
entry:
%f = alloca float
%test = icmp ne i32 %b, 0
br i1 %test, label %then, label %else
then:
br label %exit
else:
%bitcast = bitcast float* %f to i32*
br label %exit
exit:
%phi = phi i32* [ %bitcast, %else ], [ %ptr, %then ]
%loaded = load i32* %phi, align 4
ret i32 %loaded
}
define i32 @test9(i32 %b, i32* %ptr) {
; Same as @test8 but for a select rather than a PHI node.
; CHECK: @test9
; CHECK-NOT: alloca
; CHECK-NOT: load
; CHECK: %[[value:.*]] = load i32* %ptr
; CHECK-NOT: load
; CHECK: %[[result:.*]] = select i1 %{{.*}}, i32 undef, i32 %[[value]]
; CHECK-NEXT: ret i32 %[[result]]
entry:
%f = alloca float
store i32 0, i32* %ptr
%test = icmp ne i32 %b, 0
%bitcast = bitcast float* %f to i32*
%select = select i1 %test, i32* %bitcast, i32* %ptr
%loaded = load i32* %select, align 4
ret i32 %loaded
}
define i32 @test10(i32 %b, i32* %ptr) {
; Don't try to promote allocas which are not elligible for it even after
; rewriting due to the necessity of inserting bitcasts when speculating a PHI
; node.
; CHECK: @test10
; CHECK: %[[alloca:.*]] = alloca
; CHECK: %[[argvalue:.*]] = load i32* %ptr
; CHECK: %[[cast:.*]] = bitcast double* %[[alloca]] to i32*
; CHECK: %[[allocavalue:.*]] = load i32* %[[cast]]
; CHECK: %[[result:.*]] = phi i32 [ %[[allocavalue]], %else ], [ %[[argvalue]], %then ]
; CHECK-NEXT: ret i32 %[[result]]
entry:
%f = alloca double
store double 0.0, double* %f
%test = icmp ne i32 %b, 0
br i1 %test, label %then, label %else
then:
br label %exit
else:
%bitcast = bitcast double* %f to i32*
br label %exit
exit:
%phi = phi i32* [ %bitcast, %else ], [ %ptr, %then ]
%loaded = load i32* %phi, align 4
ret i32 %loaded
}
define i32 @test11(i32 %b, i32* %ptr) {
; Same as @test10 but for a select rather than a PHI node.
; CHECK: @test11
; CHECK: %[[alloca:.*]] = alloca
; CHECK: %[[cast:.*]] = bitcast double* %[[alloca]] to i32*
; CHECK: %[[allocavalue:.*]] = load i32* %[[cast]]
; CHECK: %[[argvalue:.*]] = load i32* %ptr
; CHECK: %[[result:.*]] = select i1 %{{.*}}, i32 %[[allocavalue]], i32 %[[argvalue]]
; CHECK-NEXT: ret i32 %[[result]]
entry:
%f = alloca double
store double 0.0, double* %f
store i32 0, i32* %ptr
%test = icmp ne i32 %b, 0
%bitcast = bitcast double* %f to i32*
%select = select i1 %test, i32* %bitcast, i32* %ptr
%loaded = load i32* %select, align 4
ret i32 %loaded
}
define i32 @test12(i32 %x, i32* %p) {
; Ensure we don't crash or fail to nuke dead selects of allocas if no load is
; never found.
; CHECK: @test12
; CHECK-NOT: alloca
; CHECK-NOT: select
; CHECK: ret i32 %x
entry:
%a = alloca i32
store i32 %x, i32* %a
%dead = select i1 undef, i32* %a, i32* %p
%load = load i32* %a
ret i32 %load
}
define i32 @test13(i32 %x, i32* %p) {
; Ensure we don't crash or fail to nuke dead phis of allocas if no load is ever
; found.
; CHECK: @test13
; CHECK-NOT: alloca
; CHECK-NOT: phi
; CHECK: ret i32 %x
entry:
%a = alloca i32
store i32 %x, i32* %a
br label %loop
loop:
%phi = phi i32* [ %p, %entry ], [ %a, %loop ]
br i1 undef, label %loop, label %exit
exit:
%load = load i32* %a
ret i32 %load
}
define i32 @PR13905() {
; Check a pattern where we have a chain of dead phi nodes to ensure they are
; deleted and promotion can proceed.
; CHECK: @PR13905
; CHECK-NOT: alloca i32
; CHECK: ret i32 undef
entry:
%h = alloca i32
store i32 0, i32* %h
br i1 undef, label %loop1, label %exit
loop1:
%phi1 = phi i32* [ null, %entry ], [ %h, %loop1 ], [ %h, %loop2 ]
br i1 undef, label %loop1, label %loop2
loop2:
br i1 undef, label %loop1, label %exit
exit:
%phi2 = phi i32* [ %phi1, %loop2 ], [ null, %entry ]
ret i32 undef
}
define i32 @PR13906() {
; Another pattern which can lead to crashes due to failing to clear out dead
; PHI nodes or select nodes. This triggers subtly differently from the above
; cases because the PHI node is (recursively) alive, but the select is dead.
; CHECK: @PR13906
; CHECK-NOT: alloca
entry:
%c = alloca i32
store i32 0, i32* %c
br label %for.cond
for.cond:
%d.0 = phi i32* [ undef, %entry ], [ %c, %if.then ], [ %d.0, %for.cond ]
br i1 undef, label %if.then, label %for.cond
if.then:
%tmpcast.d.0 = select i1 undef, i32* %c, i32* %d.0
br label %for.cond
}