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llvm-mirror/test/Transforms/SROA/phi-and-select.ll
Chandler Carruth 42df021931 Fix PR14132 and handle OOB loads speculated throuh PHI nodes.
The issue is that we may end up with newly OOB loads when speculating
a load into the predecessors of a PHI node, and this confuses the new
integer splitting logic in some cases, triggering an assertion failure.
In fact, the branch in question must be dead code as it loads from
a too-narrow alloca. Add code to handle this gracefully and leave the
requisite FIXMEs for both optimizing more aggressively and doing more to
aid sanitizing invalid code which triggers these patterns.

llvm-svn: 168361
2012-11-20 10:02:19 +00:00

428 lines
10 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 float @test10(i32 %b, float* %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 float* %ptr
; CHECK: %[[cast:.*]] = bitcast double* %[[alloca]] to float*
; CHECK: %[[allocavalue:.*]] = load float* %[[cast]]
; CHECK: %[[result:.*]] = phi float [ %[[allocavalue]], %else ], [ %[[argvalue]], %then ]
; CHECK-NEXT: ret float %[[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 float*
br label %exit
exit:
%phi = phi float* [ %bitcast, %else ], [ %ptr, %then ]
%loaded = load float* %phi, align 4
ret float %loaded
}
define float @test11(i32 %b, float* %ptr) {
; Same as @test10 but for a select rather than a PHI node.
; CHECK: @test11
; CHECK: %[[alloca:.*]] = alloca
; CHECK: %[[cast:.*]] = bitcast double* %[[alloca]] to float*
; CHECK: %[[allocavalue:.*]] = load float* %[[cast]]
; CHECK: %[[argvalue:.*]] = load float* %ptr
; CHECK: %[[result:.*]] = select i1 %{{.*}}, float %[[allocavalue]], float %[[argvalue]]
; CHECK-NEXT: ret float %[[result]]
entry:
%f = alloca double
store double 0.0, double* %f
store float 0.0, float* %ptr
%test = icmp ne i32 %b, 0
%bitcast = bitcast double* %f to float*
%select = select i1 %test, float* %bitcast, float* %ptr
%loaded = load float* %select, align 4
ret float %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
}
define i64 @PR14132(i1 %flag) {
; CHECK: @PR14132
; Here we form a PHI-node by promoting the pointer alloca first, and then in
; order to promote the other two allocas, we speculate the load of the
; now-phi-node-pointer. In doing so we end up loading a 64-bit value from an i8
; alloca, which is completely bogus. However, we were asserting on trying to
; rewrite it. Now it is replaced with undef. Eventually we may replace it with
; unrechable and even the CFG will go away here.
entry:
%a = alloca i64
%b = alloca i8
%ptr = alloca i64*
; CHECK-NOT: alloca
%ptr.cast = bitcast i64** %ptr to i8**
store i64 0, i64* %a
store i8 1, i8* %b
store i64* %a, i64** %ptr
br i1 %flag, label %if.then, label %if.end
if.then:
store i8* %b, i8** %ptr.cast
br label %if.end
if.end:
%tmp = load i64** %ptr
%result = load i64* %tmp
; CHECK-NOT: store
; CHECK-NOT: load
; CHECK: %[[result:.*]] = phi i64 [ undef, %if.then ], [ 0, %entry ]
ret i64 %result
; CHECK-NEXT: ret i64 %[[result]]
}