llvm-6502/test/Transforms/SROA/phi-and-select.ll
Chandler Carruth c303463dcc Fix a case where SROA did not correctly detect dead PHI or selects due
to chains or cycles between PHIs and/or selects. Also add a couple of
really nice test cases reduced from Kostya's reports in PR13905 and
PR13906. Both are fixed by this patch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164596 91177308-0d34-0410-b5e6-96231b3b80d8
2012-09-25 10:03:40 +00:00

375 lines
8.5 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
%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
; CHECK-NOT: store
switch i32 %x, label %bb0 [ i32 1, label %bb1
i32 2, label %bb2
i32 3, label %bb3 ]
bb0:
br label %exit
bb1:
br label %exit
bb2:
br label %exit
bb3:
br label %exit
exit:
%phi = phi i32* [ %a1, %bb0 ], [ %a0, %bb1 ], [ %a0, %bb2 ], [ %a1, %bb3 ]
; CHECK: phi i32 [ 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
}