371fcb720e
That transformation is lossy, as discussed in https://github.com/llvm/llvm-project/issues/53853 and https://github.com/rust-lang/rust/issues/85133#issuecomment-904185574 This is an alternative to D119839, which would add a limited IPSCCP into SimplifyCFG. Unlike lowering switch to lookup, we still want this transformation to happen relatively early, but after giving a chance for the things like CVP to do their thing. It seems like deferring it just until the IPSCCP is enough for the tests at hand, but perhaps we need to be more aggressive and disable it until CVP. Fixes https://github.com/llvm/llvm-project/issues/53853 Refs. https://github.com/rust-lang/rust/issues/85133 Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D119854
383 lines
11 KiB
LLVM
383 lines
11 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
|
|
; Test merging of blocks with phi nodes.
|
|
;
|
|
; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -switch-range-to-icmp -S | FileCheck %s
|
|
;
|
|
|
|
; ModuleID = '<stdin>'
|
|
declare i1 @foo()
|
|
|
|
declare i1 @bar(i32)
|
|
|
|
define i32 @test(i1 %a) {
|
|
; CHECK-LABEL: @test(
|
|
; CHECK-NEXT: Q:
|
|
; CHECK-NEXT: [[R:%.*]] = add i32 2, 1
|
|
; CHECK-NEXT: ret i32 [[R]]
|
|
;
|
|
Q:
|
|
br i1 %a, label %N, label %M
|
|
N: ; preds = %Q
|
|
br label %M
|
|
M: ; preds = %N, %Q
|
|
; It's ok to merge N and M because the incoming values for W are the
|
|
; same for both cases...
|
|
%W = phi i32 [ 2, %N ], [ 2, %Q ] ; <i32> [#uses=1]
|
|
%R = add i32 %W, 1 ; <i32> [#uses=1]
|
|
ret i32 %R
|
|
}
|
|
|
|
; Test merging of blocks with phi nodes where at least one incoming value
|
|
; in the successor is undef.
|
|
define i8 @testundef(i32 %u) {
|
|
; CHECK-LABEL: @testundef(
|
|
; CHECK-NEXT: R:
|
|
; CHECK-NEXT: [[U_OFF:%.*]] = add i32 [[U:%.*]], -1
|
|
; CHECK-NEXT: [[SWITCH:%.*]] = icmp ult i32 [[U_OFF]], 2
|
|
; CHECK-NEXT: [[SPEC_SELECT:%.*]] = select i1 [[SWITCH]], i8 1, i8 0
|
|
; CHECK-NEXT: ret i8 [[SPEC_SELECT]]
|
|
;
|
|
R:
|
|
switch i32 %u, label %U [
|
|
i32 0, label %S
|
|
i32 1, label %T
|
|
i32 2, label %T
|
|
]
|
|
|
|
S: ; preds = %R
|
|
br label %U
|
|
|
|
T: ; preds = %R, %R
|
|
br label %U
|
|
|
|
U: ; preds = %T, %S, %R
|
|
; We should be able to merge either the S or T block into U by rewriting
|
|
; R's incoming value with the incoming value of that predecessor since
|
|
; R's incoming value is undef and both of those predecessors are simple
|
|
; unconditional branches.
|
|
%val.0 = phi i8 [ undef, %R ], [ 1, %T ], [ 0, %S ]
|
|
ret i8 %val.0
|
|
}
|
|
|
|
; Test merging of blocks with phi nodes where at least one incoming value
|
|
; in the successor is undef.
|
|
define i8 @testundef2(i32 %u, i32* %A) {
|
|
; CHECK-LABEL: @testundef2(
|
|
; CHECK-NEXT: V:
|
|
; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[U:%.*]], 3
|
|
; CHECK-NEXT: br i1 [[COND]], label [[Z:%.*]], label [[U:%.*]]
|
|
; CHECK: Z:
|
|
; CHECK-NEXT: store i32 0, i32* [[A:%.*]], align 4
|
|
; CHECK-NEXT: br label [[U]]
|
|
; CHECK: U:
|
|
; CHECK-NEXT: ret i8 1
|
|
;
|
|
V:
|
|
switch i32 %u, label %U [
|
|
i32 0, label %W
|
|
i32 1, label %X
|
|
i32 2, label %X
|
|
i32 3, label %Z
|
|
]
|
|
|
|
W: ; preds = %V
|
|
br label %U
|
|
|
|
Z:
|
|
store i32 0, i32* %A, align 4
|
|
br label %X
|
|
|
|
X: ; preds = %V, %V, %Z
|
|
br label %U
|
|
|
|
U: ; preds = %X, %W, %V
|
|
; We should be able to merge either the W or X block into U by rewriting
|
|
; V's incoming value with the incoming value of that predecessor since
|
|
; V's incoming value is undef and both of those predecessors are simple
|
|
; unconditional branches. Note that X has predecessors beyond
|
|
; the direct predecessors of U.
|
|
%val.0 = phi i8 [ undef, %V ], [ 1, %X ], [ 1, %W ]
|
|
ret i8 %val.0
|
|
}
|
|
|
|
define i8 @testmergesome(i32 %u, i32* %A) {
|
|
; CHECK-LABEL: @testmergesome(
|
|
; CHECK-NEXT: V:
|
|
; CHECK-NEXT: switch i32 [[U:%.*]], label [[Y:%.*]] [
|
|
; CHECK-NEXT: i32 0, label [[W:%.*]]
|
|
; CHECK-NEXT: i32 3, label [[Z:%.*]]
|
|
; CHECK-NEXT: ]
|
|
; CHECK: W:
|
|
; CHECK-NEXT: store i32 1, i32* [[A:%.*]], align 4
|
|
; CHECK-NEXT: br label [[Y]]
|
|
; CHECK: Z:
|
|
; CHECK-NEXT: store i32 0, i32* [[A]], align 4
|
|
; CHECK-NEXT: br label [[Y]]
|
|
; CHECK: Y:
|
|
; CHECK-NEXT: [[VAL_0:%.*]] = phi i8 [ 2, [[W]] ], [ 1, [[Z]] ], [ 1, [[V:%.*]] ]
|
|
; CHECK-NEXT: ret i8 [[VAL_0]]
|
|
;
|
|
V:
|
|
switch i32 %u, label %Y [
|
|
i32 0, label %W
|
|
i32 1, label %X
|
|
i32 2, label %X
|
|
i32 3, label %Z
|
|
]
|
|
|
|
W: ; preds = %V
|
|
store i32 1, i32* %A, align 4
|
|
br label %Y
|
|
|
|
Z:
|
|
store i32 0, i32* %A, align 4
|
|
br label %X
|
|
|
|
X: ; preds = %V, %Z
|
|
br label %Y
|
|
|
|
Y: ; preds = %X, %W, %V
|
|
; After merging X into Y, we should have 5 predecessors
|
|
; and thus 5 incoming values to the phi.
|
|
%val.0 = phi i8 [ 1, %V ], [ 1, %X ], [ 2, %W ]
|
|
ret i8 %val.0
|
|
}
|
|
|
|
|
|
define i8 @testmergesome2(i32 %u, i32* %A) {
|
|
; CHECK-LABEL: @testmergesome2(
|
|
; CHECK-NEXT: V:
|
|
; CHECK-NEXT: switch i32 [[U:%.*]], label [[W:%.*]] [
|
|
; CHECK-NEXT: i32 4, label [[Y:%.*]]
|
|
; CHECK-NEXT: i32 1, label [[Y]]
|
|
; CHECK-NEXT: i32 2, label [[Y]]
|
|
; CHECK-NEXT: ]
|
|
; CHECK: W:
|
|
; CHECK-NEXT: store i32 1, i32* [[A:%.*]], align 4
|
|
; CHECK-NEXT: br label [[Y]]
|
|
; CHECK: Y:
|
|
; CHECK-NEXT: [[VAL_0:%.*]] = phi i8 [ 1, [[V:%.*]] ], [ 2, [[W]] ], [ 1, [[V]] ], [ 1, [[V]] ]
|
|
; CHECK-NEXT: ret i8 [[VAL_0]]
|
|
;
|
|
V:
|
|
switch i32 %u, label %W [
|
|
i32 0, label %W
|
|
i32 1, label %Y
|
|
i32 2, label %X
|
|
i32 4, label %Y
|
|
]
|
|
|
|
W: ; preds = %V
|
|
store i32 1, i32* %A, align 4
|
|
br label %Y
|
|
|
|
X: ; preds = %V, %Z
|
|
br label %Y
|
|
|
|
Y: ; preds = %X, %W, %V
|
|
; Ensure that we deal with both undef inputs for V when we merge in X.
|
|
%val.0 = phi i8 [ undef, %V ], [ 1, %X ], [ 2, %W ], [ undef, %V ]
|
|
ret i8 %val.0
|
|
}
|
|
|
|
; This function can't be merged
|
|
define void @a() {
|
|
; CHECK-LABEL: @a(
|
|
; CHECK-NEXT: entry:
|
|
; CHECK-NEXT: br label [[BB_NOMERGE:%.*]]
|
|
; CHECK: BB.nomerge:
|
|
; CHECK-NEXT: [[A:%.*]] = phi i32 [ 1, [[ENTRY:%.*]] ], [ 0, [[COMMON:%.*]] ]
|
|
; CHECK-NEXT: br label [[SUCC:%.*]]
|
|
; CHECK: Succ:
|
|
; CHECK-NEXT: [[B:%.*]] = phi i32 [ [[A]], [[BB_NOMERGE]] ], [ 2, [[COMMON]] ]
|
|
; CHECK-NEXT: [[CONDE:%.*]] = call i1 @foo()
|
|
; CHECK-NEXT: br i1 [[CONDE]], label [[COMMON]], label [[EXIT:%.*]]
|
|
; CHECK: Common:
|
|
; CHECK-NEXT: [[COND:%.*]] = call i1 @foo()
|
|
; CHECK-NEXT: br i1 [[COND]], label [[BB_NOMERGE]], label [[SUCC]]
|
|
; CHECK: Exit:
|
|
; CHECK-NEXT: ret void
|
|
;
|
|
entry:
|
|
br label %BB.nomerge
|
|
|
|
BB.nomerge: ; preds = %Common, %entry
|
|
; This phi has a conflicting value (0) with below phi (2), so blocks
|
|
; can't be merged.
|
|
%a = phi i32 [ 1, %entry ], [ 0, %Common ] ; <i32> [#uses=1]
|
|
br label %Succ
|
|
|
|
Succ: ; preds = %Common, %BB.nomerge
|
|
%b = phi i32 [ %a, %BB.nomerge ], [ 2, %Common ] ; <i32> [#uses=0]
|
|
%conde = call i1 @foo( ) ; <i1> [#uses=1]
|
|
br i1 %conde, label %Common, label %Exit
|
|
|
|
Common: ; preds = %Succ
|
|
%cond = call i1 @foo( ) ; <i1> [#uses=1]
|
|
br i1 %cond, label %BB.nomerge, label %Succ
|
|
|
|
Exit: ; preds = %Succ
|
|
ret void
|
|
}
|
|
|
|
; This function can't be merged
|
|
define void @b() {
|
|
; CHECK-LABEL: @b(
|
|
; CHECK-NEXT: entry:
|
|
; CHECK-NEXT: br label [[BB_NOMERGE:%.*]]
|
|
; CHECK: BB.nomerge:
|
|
; CHECK-NEXT: br label [[SUCC:%.*]]
|
|
; CHECK: Succ:
|
|
; CHECK-NEXT: [[B:%.*]] = phi i32 [ 1, [[BB_NOMERGE]] ], [ 2, [[COMMON:%.*]] ]
|
|
; CHECK-NEXT: [[CONDE:%.*]] = call i1 @foo()
|
|
; CHECK-NEXT: br i1 [[CONDE]], label [[COMMON]], label [[EXIT:%.*]]
|
|
; CHECK: Common:
|
|
; CHECK-NEXT: [[COND:%.*]] = call i1 @foo()
|
|
; CHECK-NEXT: br i1 [[COND]], label [[BB_NOMERGE]], label [[SUCC]]
|
|
; CHECK: Exit:
|
|
; CHECK-NEXT: ret void
|
|
;
|
|
entry:
|
|
br label %BB.nomerge
|
|
|
|
BB.nomerge: ; preds = %Common, %entry
|
|
br label %Succ
|
|
|
|
Succ: ; preds = %Common, %BB.nomerge
|
|
; This phi has confliction values for Common and (through BB) Common,
|
|
; blocks can't be merged
|
|
%b = phi i32 [ 1, %BB.nomerge ], [ 2, %Common ] ; <i32> [#uses=0]
|
|
%conde = call i1 @foo( ) ; <i1> [#uses=1]
|
|
br i1 %conde, label %Common, label %Exit
|
|
|
|
Common: ; preds = %Succ
|
|
%cond = call i1 @foo( ) ; <i1> [#uses=1]
|
|
br i1 %cond, label %BB.nomerge, label %Succ
|
|
|
|
Exit: ; preds = %Succ
|
|
ret void
|
|
}
|
|
|
|
; This function can't be merged (for keeping canonical loop structures)
|
|
define void @c() {
|
|
; CHECK-LABEL: @c(
|
|
; CHECK-NEXT: entry:
|
|
; CHECK-NEXT: br label [[BB_NOMERGE:%.*]]
|
|
; CHECK: BB.nomerge:
|
|
; CHECK-NEXT: br label [[SUCC:%.*]]
|
|
; CHECK: Succ:
|
|
; CHECK-NEXT: [[B:%.*]] = phi i32 [ 1, [[BB_NOMERGE]] ], [ 1, [[COMMON:%.*]] ], [ 2, [[PRE_EXIT:%.*]] ]
|
|
; CHECK-NEXT: [[CONDE:%.*]] = call i1 @foo()
|
|
; CHECK-NEXT: br i1 [[CONDE]], label [[COMMON]], label [[PRE_EXIT]]
|
|
; CHECK: Common:
|
|
; CHECK-NEXT: [[COND:%.*]] = call i1 @foo()
|
|
; CHECK-NEXT: br i1 [[COND]], label [[BB_NOMERGE]], label [[SUCC]]
|
|
; CHECK: Pre-Exit:
|
|
; CHECK-NEXT: [[COND2:%.*]] = call i1 @foo()
|
|
; CHECK-NEXT: br i1 [[COND2]], label [[SUCC]], label [[EXIT:%.*]]
|
|
; CHECK: Exit:
|
|
; CHECK-NEXT: ret void
|
|
;
|
|
entry:
|
|
br label %BB.nomerge
|
|
|
|
BB.nomerge: ; preds = %Common, %entry
|
|
br label %Succ
|
|
|
|
Succ: ; preds = %Common, %BB.tomerge, %Pre-Exit
|
|
; This phi has identical values for Common and (through BB) Common,
|
|
; blocks can't be merged
|
|
%b = phi i32 [ 1, %BB.nomerge ], [ 1, %Common ], [ 2, %Pre-Exit ]
|
|
%conde = call i1 @foo( ) ; <i1> [#uses=1]
|
|
br i1 %conde, label %Common, label %Pre-Exit
|
|
|
|
Common: ; preds = %Succ
|
|
%cond = call i1 @foo( ) ; <i1> [#uses=1]
|
|
br i1 %cond, label %BB.nomerge, label %Succ
|
|
|
|
Pre-Exit: ; preds = %Succ
|
|
; This adds a backedge, so the %b phi node gets a third branch and is
|
|
; not completely trivial
|
|
%cond2 = call i1 @foo( ) ; <i1> [#uses=1]
|
|
br i1 %cond2, label %Succ, label %Exit
|
|
|
|
Exit: ; preds = %Pre-Exit
|
|
ret void
|
|
}
|
|
|
|
; This function can't be merged (for keeping canonical loop structures)
|
|
define void @d() {
|
|
; CHECK-LABEL: @d(
|
|
; CHECK-NEXT: entry:
|
|
; CHECK-NEXT: br label [[BB_NOMERGE:%.*]]
|
|
; CHECK: BB.nomerge:
|
|
; CHECK-NEXT: [[A:%.*]] = phi i32 [ 1, [[ENTRY:%.*]] ], [ 0, [[COMMON:%.*]] ]
|
|
; CHECK-NEXT: br label [[SUCC:%.*]]
|
|
; CHECK: Succ:
|
|
; CHECK-NEXT: [[B:%.*]] = phi i32 [ [[A]], [[BB_NOMERGE]] ], [ 0, [[COMMON]] ]
|
|
; CHECK-NEXT: [[CONDE:%.*]] = call i1 @foo()
|
|
; CHECK-NEXT: br i1 [[CONDE]], label [[COMMON]], label [[EXIT:%.*]]
|
|
; CHECK: Common:
|
|
; CHECK-NEXT: [[COND:%.*]] = call i1 @foo()
|
|
; CHECK-NEXT: br i1 [[COND]], label [[BB_NOMERGE]], label [[SUCC]]
|
|
; CHECK: Exit:
|
|
; CHECK-NEXT: ret void
|
|
;
|
|
entry:
|
|
br label %BB.nomerge
|
|
|
|
BB.nomerge: ; preds = %Common, %entry
|
|
; This phi has a matching value (0) with below phi (0), so blocks
|
|
; can be merged.
|
|
%a = phi i32 [ 1, %entry ], [ 0, %Common ] ; <i32> [#uses=1]
|
|
br label %Succ
|
|
|
|
Succ: ; preds = %Common, %BB.tomerge
|
|
%b = phi i32 [ %a, %BB.nomerge ], [ 0, %Common ] ; <i32> [#uses=0]
|
|
%conde = call i1 @foo( ) ; <i1> [#uses=1]
|
|
br i1 %conde, label %Common, label %Exit
|
|
|
|
Common: ; preds = %Succ
|
|
%cond = call i1 @foo( ) ; <i1> [#uses=1]
|
|
br i1 %cond, label %BB.nomerge, label %Succ
|
|
|
|
Exit: ; preds = %Succ
|
|
ret void
|
|
}
|
|
|
|
; This function can be merged
|
|
define void @e() {
|
|
; CHECK-LABEL: @e(
|
|
; CHECK-NEXT: entry:
|
|
; CHECK-NEXT: br label [[SUCC:%.*]]
|
|
; CHECK: Succ:
|
|
; CHECK-NEXT: [[A:%.*]] = phi i32 [ 1, [[ENTRY:%.*]] ], [ 0, [[USE:%.*]] ]
|
|
; CHECK-NEXT: [[CONDE:%.*]] = call i1 @foo()
|
|
; CHECK-NEXT: br i1 [[CONDE]], label [[USE]], label [[EXIT:%.*]]
|
|
; CHECK: Use:
|
|
; CHECK-NEXT: [[COND:%.*]] = call i1 @bar(i32 [[A]])
|
|
; CHECK-NEXT: br i1 [[COND]], label [[SUCC]], label [[EXIT]]
|
|
; CHECK: Exit:
|
|
; CHECK-NEXT: ret void
|
|
;
|
|
entry:
|
|
br label %Succ
|
|
|
|
Succ: ; preds = %Use, %entry
|
|
; This phi is used somewhere else than Succ, but this should not prevent
|
|
; merging this block
|
|
%a = phi i32 [ 1, %entry ], [ 0, %Use ] ; <i32> [#uses=1]
|
|
br label %BB.tomerge
|
|
|
|
BB.tomerge: ; preds = %Succ
|
|
%conde = call i1 @foo( ) ; <i1> [#uses=1]
|
|
br i1 %conde, label %Use, label %Exit
|
|
|
|
Use: ; preds = %Succ
|
|
%cond = call i1 @bar( i32 %a ) ; <i1> [#uses=1]
|
|
br i1 %cond, label %Succ, label %Exit
|
|
|
|
Exit: ; preds = %Use, %Succ
|
|
ret void
|
|
}
|