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12 changes: 12 additions & 0 deletions llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/ProfDataUtils.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Scalar/LoopPassManager.h"
Expand Down Expand Up @@ -393,6 +394,17 @@ class ConstantTerminatorFoldingImpl {
DTUpdates.push_back({DominatorTree::Insert, Preheader, BB});
++NumLoopExitsDeleted;
}
// We don't really need to add branch weights to DummySwitch, because all
// but one branches are just a temporary artifact - see the comment on top
// of this function. But, it's easy to estimate the weights, and it helps
// maintain a property of the overall compiler - that the branch weights
// don't "just get dropped" accidentally (i.e. profcheck)
if (DummySwitch->getParent()->getParent()->hasProfileData()) {
SmallVector<uint32_t> DummyBranchWeights(1 + DummySwitch->getNumCases());
// default. 100% probability, the rest are dead.
DummyBranchWeights[0] = 1;
setBranchWeights(*DummySwitch, DummyBranchWeights, /*IsExpected=*/false);
}

assert(L.getLoopPreheader() == NewPreheader && "Malformed CFG?");
if (Loop *OuterLoop = LI.getLoopFor(Preheader)) {
Expand Down
104 changes: 54 additions & 50 deletions llvm/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals
; REQUIRES: asserts
; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -passes=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa < %s | FileCheck %s
; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -passes='require<domtree>,loop(loop-simplifycfg)' -verify-loop-info -verify-dom-info -verify-loop-lcssa < %s | FileCheck %s
Expand Down Expand Up @@ -59,7 +59,7 @@ define i32 @dead_backedge_test_switch_loop(i32 %end) {
; CHECK: dead_backedge:
; CHECK-NEXT: [[I_2]] = add i32 [[I_1]], 10
; CHECK-NEXT: switch i32 1, label [[EXIT:%.*]] [
; CHECK-NEXT: i32 0, label [[HEADER_BACKEDGE]]
; CHECK-NEXT: i32 0, label [[HEADER_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: exit:
; CHECK-NEXT: [[I_2_LCSSA:%.*]] = phi i32 [ [[I_2]], [[DEAD_BACKEDGE]] ]
Expand Down Expand Up @@ -233,12 +233,12 @@ exit:

; Check that we preserve static reachibility of a dead exit block while deleting
; a branch.
define i32 @dead_exit_test_branch_loop(i32 %end) {
define i32 @dead_exit_test_branch_loop(i32 %end) !prof !{!"function_entry_count", i32 10} {
; CHECK-LABEL: @dead_exit_test_branch_loop(
; CHECK-NEXT: preheader:
; CHECK-NEXT: switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[DEAD:%.*]]
; CHECK-NEXT: ]
; CHECK-NEXT: i32 1, label [[DEAD:%.*]]
; CHECK-NEXT: ], !prof [[PROF1:![0-9]+]]
; CHECK: preheader.split:
; CHECK-NEXT: br label [[HEADER:%.*]]
; CHECK: header:
Expand All @@ -262,7 +262,7 @@ preheader:

header:
%i = phi i32 [0, %preheader], [%i.inc, %backedge]
br i1 true, label %backedge, label %dead
br i1 true, label %backedge, label %dead, !prof !{!"branch_weights", i32 10, i32 1}

dead:
br label %dummy
Expand All @@ -286,7 +286,7 @@ define i32 @dead_exit_test_switch_loop(i32 %end) {
; CHECK-LABEL: @dead_exit_test_switch_loop(
; CHECK-NEXT: preheader:
; CHECK-NEXT: switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[DEAD:%.*]]
; CHECK-NEXT: i32 1, label [[DEAD:%.*]]
; CHECK-NEXT: ]
; CHECK: preheader.split:
; CHECK-NEXT: br label [[HEADER:%.*]]
Expand Down Expand Up @@ -383,9 +383,9 @@ define i32 @dead_loop_test_switch_loop(i32 %end) {
; CHECK: header:
; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
; CHECK-NEXT: switch i32 1, label [[DEAD:%.*]] [
; CHECK-NEXT: i32 0, label [[DEAD]]
; CHECK-NEXT: i32 1, label [[BACKEDGE]]
; CHECK-NEXT: i32 2, label [[DEAD]]
; CHECK-NEXT: i32 0, label [[DEAD]]
; CHECK-NEXT: i32 1, label [[BACKEDGE]]
; CHECK-NEXT: i32 2, label [[DEAD]]
; CHECK-NEXT: ]
; CHECK: dead:
; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
Expand Down Expand Up @@ -552,7 +552,7 @@ define i32 @inf_loop_test_branch_loop(i32 %end) {
; CHECK-LABEL: @inf_loop_test_branch_loop(
; CHECK-NEXT: preheader:
; CHECK-NEXT: switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[EXIT:%.*]]
; CHECK-NEXT: i32 1, label [[EXIT:%.*]]
; CHECK-NEXT: ]
; CHECK: preheader.split:
; CHECK-NEXT: br label [[HEADER:%.*]]
Expand Down Expand Up @@ -592,7 +592,7 @@ define i32 @inf_loop_test_switch_loop(i32 %end) {
; CHECK-LABEL: @inf_loop_test_switch_loop(
; CHECK-NEXT: preheader:
; CHECK-NEXT: switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[EXIT:%.*]]
; CHECK-NEXT: i32 1, label [[EXIT:%.*]]
; CHECK-NEXT: ]
; CHECK: preheader.split:
; CHECK-NEXT: br label [[HEADER:%.*]]
Expand Down Expand Up @@ -1001,7 +1001,7 @@ define i32 @full_sub_loop_test_switch_loop(i32 %end) {
; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[OUTER_HEADER]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[I]], [[I]]
; CHECK-NEXT: switch i32 1, label [[DEAD:%.*]] [
; CHECK-NEXT: i32 0, label [[BACKEDGE]]
; CHECK-NEXT: i32 0, label [[BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: dead:
; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
Expand All @@ -1010,7 +1010,7 @@ define i32 @full_sub_loop_test_switch_loop(i32 %end) {
; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[I]], [[HEADER]] ], [ [[I_2]], [[DEAD]] ]
; CHECK-NEXT: [[I_INC]] = add i32 [[I_1]], 1
; CHECK-NEXT: switch i32 1, label [[OUTER_BACKEDGE]] [
; CHECK-NEXT: i32 0, label [[HEADER]]
; CHECK-NEXT: i32 0, label [[HEADER]]
; CHECK-NEXT: ]
; CHECK: outer_backedge:
; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
Expand Down Expand Up @@ -1132,7 +1132,7 @@ define i32 @full_sub_loop_test_switch_loop_inverse_1(i32 %end) {
; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[OUTER_HEADER]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[I]], [[I]]
; CHECK-NEXT: switch i32 1, label [[BACKEDGE]] [
; CHECK-NEXT: i32 0, label [[DEAD:%.*]]
; CHECK-NEXT: i32 0, label [[DEAD:%.*]]
; CHECK-NEXT: ]
; CHECK: dead:
; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
Expand All @@ -1141,7 +1141,7 @@ define i32 @full_sub_loop_test_switch_loop_inverse_1(i32 %end) {
; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[I]], [[HEADER]] ], [ [[I_2]], [[DEAD]] ]
; CHECK-NEXT: [[I_INC]] = add i32 [[I_1]], 1
; CHECK-NEXT: switch i32 1, label [[OUTER_BACKEDGE]] [
; CHECK-NEXT: i32 0, label [[HEADER]]
; CHECK-NEXT: i32 0, label [[HEADER]]
; CHECK-NEXT: ]
; CHECK: outer_backedge:
; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
Expand Down Expand Up @@ -1195,7 +1195,7 @@ define i32 @full_sub_loop_test_branch_loop_inverse_2(i32 %end) {
; CHECK: outer_header:
; CHECK-NEXT: [[J:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[J_INC:%.*]], [[OUTER_BACKEDGE:%.*]] ]
; CHECK-NEXT: switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[OUTER_BACKEDGE]]
; CHECK-NEXT: i32 1, label [[OUTER_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: preheader.split:
; CHECK-NEXT: br label [[HEADER:%.*]]
Expand Down Expand Up @@ -1256,7 +1256,7 @@ define i32 @full_sub_loop_test_switch_loop_inverse_2(i32 %end) {
; CHECK: outer_header:
; CHECK-NEXT: [[J:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[J_INC:%.*]], [[OUTER_BACKEDGE:%.*]] ]
; CHECK-NEXT: switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[OUTER_BACKEDGE]]
; CHECK-NEXT: i32 1, label [[OUTER_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: preheader.split:
; CHECK-NEXT: br label [[HEADER:%.*]]
Expand Down Expand Up @@ -1318,7 +1318,7 @@ define i32 @full_sub_loop_test_branch_loop_inverse_3(i32 %end) {
; CHECK: outer_header:
; CHECK-NEXT: [[J:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[J_INC:%.*]], [[OUTER_BACKEDGE:%.*]] ]
; CHECK-NEXT: switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[OUTER_BACKEDGE]]
; CHECK-NEXT: i32 1, label [[OUTER_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: preheader.split:
; CHECK-NEXT: br label [[HEADER:%.*]]
Expand Down Expand Up @@ -1378,7 +1378,7 @@ define i32 @full_sub_loop_test_switch_loop_inverse_3(i32 %end) {
; CHECK: outer_header:
; CHECK-NEXT: [[J:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[J_INC:%.*]], [[OUTER_BACKEDGE:%.*]] ]
; CHECK-NEXT: switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[OUTER_BACKEDGE]]
; CHECK-NEXT: i32 1, label [[OUTER_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: preheader.split:
; CHECK-NEXT: br label [[HEADER:%.*]]
Expand Down Expand Up @@ -1441,7 +1441,7 @@ define i32 @exit_branch_from_inner_to_grandparent(i1 %cond1, i1 %cond2, i32 %N)
; CHECK: loop_2:
; CHECK-NEXT: [[J:%.*]] = phi i32 [ 0, [[LOOP_1]] ], [ [[J_NEXT:%.*]], [[LOOP_2_BACKEDGE:%.*]] ]
; CHECK-NEXT: switch i32 0, label [[LOOP_2_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[LOOP_2_BACKEDGE]]
; CHECK-NEXT: i32 1, label [[LOOP_2_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: loop_2.split:
; CHECK-NEXT: br label [[LOOP_3:%.*]]
Expand Down Expand Up @@ -1510,7 +1510,7 @@ define i32 @exit_switch_from_inner_to_grandparent(i1 %cond1, i1 %cond2, i32 %N)
; CHECK: loop_2:
; CHECK-NEXT: [[J:%.*]] = phi i32 [ 0, [[LOOP_1]] ], [ [[J_NEXT:%.*]], [[LOOP_2_BACKEDGE:%.*]] ]
; CHECK-NEXT: switch i32 0, label [[LOOP_2_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[LOOP_2_BACKEDGE]]
; CHECK-NEXT: i32 1, label [[LOOP_2_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: loop_2.split:
; CHECK-NEXT: br label [[LOOP_3:%.*]]
Expand Down Expand Up @@ -1654,7 +1654,7 @@ define i32 @intermediate_switch_from_inner_to_grandparent(i1 %cond1, i1 %cond2,
; CHECK-NEXT: br i1 [[COND1:%.*]], label [[LOOP_3_BACKEDGE]], label [[INTERMEDIATE:%.*]]
; CHECK: intermediate:
; CHECK-NEXT: switch i32 1, label [[LOOP_1_BACKEDGE_LOOPEXIT:%.*]] [
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: loop_3_backedge:
; CHECK-NEXT: [[K_NEXT]] = add i32 [[K]], 1
Expand Down Expand Up @@ -1792,7 +1792,7 @@ define i32 @intermediate_switch_from_inner_to_parent(i1 %cond1, i1 %cond2, i32 %
; CHECK-NEXT: br i1 [[COND1:%.*]], label [[LOOP_3_BACKEDGE]], label [[INTERMEDIATE:%.*]]
; CHECK: intermediate:
; CHECK-NEXT: switch i32 1, label [[LOOP_2_BACKEDGE]] [
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: loop_3_backedge:
; CHECK-NEXT: [[K_NEXT]] = add i32 [[K]], 1
Expand Down Expand Up @@ -1944,7 +1944,7 @@ define i32 @intermediate_subloop_switch_from_inner_to_grandparent(i1 %cond1, i1
; CHECK-NEXT: br i1 [[COND3:%.*]], label [[INTERMEDIATE_LOOP]], label [[INTERMEDIATE_EXIT:%.*]]
; CHECK: intermediate_exit:
; CHECK-NEXT: switch i32 1, label [[LOOP_1_BACKEDGE_LOOPEXIT:%.*]] [
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: loop_3_backedge:
; CHECK-NEXT: [[K_NEXT]] = add i32 [[K]], 1
Expand Down Expand Up @@ -2102,7 +2102,7 @@ define i32 @intermediate_subloop_switch_from_inner_to_parent(i1 %cond1, i1 %cond
; CHECK-NEXT: br i1 [[COND3:%.*]], label [[INTERMEDIATE_LOOP]], label [[INTERMEDIATE_EXIT:%.*]]
; CHECK: intermediate_exit:
; CHECK-NEXT: switch i32 1, label [[LOOP_2_BACKEDGE]] [
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: loop_3_backedge:
; CHECK-NEXT: [[K_NEXT]] = add i32 [[K]], 1
Expand Down Expand Up @@ -2267,7 +2267,7 @@ define i32 @intermediate_complex_subloop_switch_from_inner_to_parent(i1 %cond1,
; CHECK-NEXT: br i1 [[COND2:%.*]], label [[INTERMEDIATE_LOOP_BACKEDGE]], label [[INTERMEDIATE_EXIT:%.*]]
; CHECK: intermediate_exit:
; CHECK-NEXT: switch i32 1, label [[LOOP_2_BACKEDGE]] [
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: loop_3_backedge:
; CHECK-NEXT: [[K_NEXT]] = add i32 [[K]], 1
Expand Down Expand Up @@ -2440,7 +2440,7 @@ define i32 @intermediate_complex_subloop_switch_from_inner_to_grandparent(i1 %co
; CHECK-NEXT: br i1 [[COND2:%.*]], label [[INTERMEDIATE_LOOP_BACKEDGE]], label [[INTERMEDIATE_EXIT:%.*]]
; CHECK: intermediate_exit:
; CHECK-NEXT: switch i32 1, label [[LOOP_1_BACKEDGE_LOOPEXIT:%.*]] [
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: i32 0, label [[LOOP_3_BACKEDGE]]
; CHECK-NEXT: ]
; CHECK: loop_3_backedge:
; CHECK-NEXT: [[K_NEXT]] = add i32 [[K]], 1
Expand Down Expand Up @@ -2585,38 +2585,38 @@ define void @test_crash_01(i1 %arg, i32 %arg2) {
; CHECK-NEXT: bb:
; CHECK-NEXT: br label [[BB1:%.*]]
; CHECK: bb1:
; CHECK-NEXT: br i1 %arg, label [[BB17:%.*]], label [[BB2:%.*]]
; CHECK-NEXT: br i1 [[ARG:%.*]], label [[BB17:%.*]], label [[BB2:%.*]]
; CHECK: bb2:
; CHECK-NEXT: switch i32 0, label [[BB2_SPLIT:%.*]] [
; CHECK-NEXT: i32 1, label [[BB19:%.*]]
; CHECK-NEXT: i32 1, label [[BB19:%.*]]
; CHECK-NEXT: ]
; CHECK: bb2.split:
; CHECK-NEXT: br label [[BB3:%.*]]
; CHECK: bb3:
; CHECK-NEXT: switch i32 %arg2, label [[BB16:%.*]] [
; CHECK-NEXT: i32 0, label [[BB15:%.*]]
; CHECK-NEXT: i32 1, label [[BB14:%.*]]
; CHECK-NEXT: i32 2, label [[BB13:%.*]]
; CHECK-NEXT: i32 3, label [[BB12:%.*]]
; CHECK-NEXT: i32 4, label [[BB11:%.*]]
; CHECK-NEXT: i32 5, label [[BB8:%.*]]
; CHECK-NEXT: i32 6, label [[BB10:%.*]]
; CHECK-NEXT: i32 7, label [[BB9:%.*]]
; CHECK-NEXT: i32 8, label [[BB7:%.*]]
; CHECK-NEXT: switch i32 [[ARG2:%.*]], label [[BB16:%.*]] [
; CHECK-NEXT: i32 0, label [[BB15:%.*]]
; CHECK-NEXT: i32 1, label [[BB14:%.*]]
; CHECK-NEXT: i32 2, label [[BB13:%.*]]
; CHECK-NEXT: i32 3, label [[BB12:%.*]]
; CHECK-NEXT: i32 4, label [[BB11:%.*]]
; CHECK-NEXT: i32 5, label [[BB8:%.*]]
; CHECK-NEXT: i32 6, label [[BB10:%.*]]
; CHECK-NEXT: i32 7, label [[BB9:%.*]]
; CHECK-NEXT: i32 8, label [[BB7:%.*]]
; CHECK-NEXT: ]
; CHECK: bb7:
; CHECK-NEXT: unreachable
; CHECK: bb8:
; CHECK-NEXT: switch i32 %arg2, label [[BB28:%.*]] [
; CHECK-NEXT: i32 0, label [[BB27:%.*]]
; CHECK-NEXT: i32 1, label [[BB26:%.*]]
; CHECK-NEXT: i32 2, label [[BB23:%.*]]
; CHECK-NEXT: i32 3, label [[BB24:%.*]]
; CHECK-NEXT: i32 4, label [[BB25:%.*]]
; CHECK-NEXT: i32 5, label [[BB29:%.*]]
; CHECK-NEXT: i32 6, label [[BB22:%.*]]
; CHECK-NEXT: i32 7, label [[BB20:%.*]]
; CHECK-NEXT: i32 8, label [[BB21:%.*]]
; CHECK-NEXT: switch i32 [[ARG2]], label [[BB28:%.*]] [
; CHECK-NEXT: i32 0, label [[BB27:%.*]]
; CHECK-NEXT: i32 1, label [[BB26:%.*]]
; CHECK-NEXT: i32 2, label [[BB23:%.*]]
; CHECK-NEXT: i32 3, label [[BB24:%.*]]
; CHECK-NEXT: i32 4, label [[BB25:%.*]]
; CHECK-NEXT: i32 5, label [[BB29:%.*]]
; CHECK-NEXT: i32 6, label [[BB22:%.*]]
; CHECK-NEXT: i32 7, label [[BB20:%.*]]
; CHECK-NEXT: i32 8, label [[BB21:%.*]]
; CHECK-NEXT: ]
; CHECK: bb9:
; CHECK-NEXT: unreachable
Expand Down Expand Up @@ -2772,3 +2772,7 @@ bb28: ; preds = %bb8
bb29: ; preds = %bb8
br label %bb6
}
;.
; CHECK: [[META0:![0-9]+]] = !{!"function_entry_count", i32 10}
; CHECK: [[PROF1]] = !{!"branch_weights", i32 1, i32 0}
;.
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