[llvm] r307909 - [RuntimeUnrolling] Update DomTree correctly when exit blocks have successors
Anna Thomas via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 13 06:21:23 PDT 2017
Author: annat
Date: Thu Jul 13 06:21:23 2017
New Revision: 307909
URL: http://llvm.org/viewvc/llvm-project?rev=307909&view=rev
Log:
[RuntimeUnrolling] Update DomTree correctly when exit blocks have successors
Summary:
When we runtime unroll with multiple exit blocks, we also need to update the
immediate dominators of the immediate successors of the exit blocks.
Reviewers: reames, mkuper, mzolotukhin, apilipenko
Reviewed by: mzolotukhin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35304
Added:
llvm/trunk/test/Transforms/LoopUnroll/runtime-loop-multiexit-dom-verify.ll
Modified:
llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
Modified: llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp?rev=307909&r1=307908&r2=307909&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp Thu Jul 13 06:21:23 2017
@@ -22,6 +22,7 @@
//===----------------------------------------------------------------------===//
#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/LoopIterator.h"
#include "llvm/Analysis/LoopPass.h"
@@ -736,7 +737,9 @@ bool llvm::UnrollRuntimeLoopRemainder(Lo
// remainder are connected to the original Loop's exit blocks. The remaining
// work is to update the phi nodes in the original loop, and take in the
// values from the cloned region. Also update the dominator info for
- // OtherExits, since we have new edges into OtherExits.
+ // OtherExits and their immediate successors, since we have new edges into
+ // OtherExits.
+ SmallSet<BasicBlock*, 8> ImmediateSuccessorsOfExitBlocks;
for (auto *BB : OtherExits) {
for (auto &II : *BB) {
@@ -759,12 +762,35 @@ bool llvm::UnrollRuntimeLoopRemainder(Lo
cast<BasicBlock>(VMap[Phi->getIncomingBlock(i)]));
}
}
+#ifdef EXPENSIVE_CHECKS
+ for (BasicBlock *SuccBB : successors(BB)) {
+ assert(!(any_of(OtherExits,
+ [SuccBB](BasicBlock *EB) { return EB == SuccBB; }) ||
+ SuccBB == LatchExit) &&
+ "Breaks the definition of dedicated exits!");
+ }
+#endif
// Update the dominator info because the immediate dominator is no longer the
// header of the original Loop. BB has edges both from L and remainder code.
// Since the preheader determines which loop is run (L or directly jump to
// the remainder code), we set the immediate dominator as the preheader.
- if (DT)
+ if (DT) {
DT->changeImmediateDominator(BB, PreHeader);
+ // Also update the IDom for immediate successors of BB. If the current
+ // IDom is the header, update the IDom to be the preheader because that is
+ // the nearest common dominator of all predecessors of SuccBB. We need to
+ // check for IDom being the header because successors of exit blocks can
+ // have edges from outside the loop, and we should not incorrectly update
+ // the IDom in that case.
+ for (BasicBlock *SuccBB: successors(BB))
+ if (ImmediateSuccessorsOfExitBlocks.insert(SuccBB).second) {
+ if (DT->getNode(SuccBB)->getIDom()->getBlock() == Header) {
+ assert(!SuccBB->getSinglePredecessor() &&
+ "BB should be the IDom then!");
+ DT->changeImmediateDominator(SuccBB, PreHeader);
+ }
+ }
+ }
}
// Loop structure should be the following:
Added: llvm/trunk/test/Transforms/LoopUnroll/runtime-loop-multiexit-dom-verify.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/runtime-loop-multiexit-dom-verify.ll?rev=307909&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/runtime-loop-multiexit-dom-verify.ll (added)
+++ llvm/trunk/test/Transforms/LoopUnroll/runtime-loop-multiexit-dom-verify.ll Thu Jul 13 06:21:23 2017
@@ -0,0 +1,126 @@
+; RUN: opt < %s -loop-unroll -unroll-runtime=true -unroll-runtime-epilog=false -unroll-runtime-multi-exit=true -unroll-count=4 -verify-dom-info -S | FileCheck %s
+
+; REQUIRES: asserts
+; The tests below are for verifying dom tree after runtime unrolling
+; with multiple exit/exiting blocks.
+
+; We explicitly set the unroll count so that expensiveTripCount computation is allowed.
+
+; mergedexit block has edges from loop exit blocks.
+define i64 @test1() {
+; CHECK-LABEL: test1(
+; CHECK-LABEL: headerexit:
+; CHECK-NEXT: %addphi = phi i64 [ %add.iv, %header ], [ %add.iv.1, %header.1 ], [ %add.iv.2, %header.2 ], [ %add.iv.3, %header.3 ]
+; CHECK-NEXT: br label %mergedexit
+; CHECK-LABEL: latchexit:
+; CHECK-NEXT: %shftphi = phi i64 [ %shft, %latch ], [ %shft.1, %latch.1 ], [ %shft.2, %latch.2 ], [ %shft.3, %latch.3 ]
+; CHECK-NEXT: br label %mergedexit
+; CHECK-LABEL: mergedexit:
+; CHECK-NEXT: %retval = phi i64 [ %addphi, %headerexit ], [ %shftphi, %latchexit ]
+; CHECK-NEXT: ret i64 %retval
+entry:
+ br label %preheader
+
+preheader: ; preds = %bb
+ %trip = zext i32 undef to i64
+ br label %header
+
+header: ; preds = %latch, %preheader
+ %iv = phi i64 [ 2, %preheader ], [ %add.iv, %latch ]
+ %add.iv = add nuw nsw i64 %iv, 2
+ %cmp1 = icmp ult i64 %add.iv, %trip
+ br i1 %cmp1, label %latch, label %headerexit
+
+latch: ; preds = %header
+ %shft = ashr i64 %add.iv, 1
+ %cmp2 = icmp ult i64 %shft, %trip
+ br i1 %cmp2, label %header, label %latchexit
+
+headerexit: ; preds = %header
+ %addphi = phi i64 [ %add.iv, %header ]
+ br label %mergedexit
+
+latchexit: ; preds = %latch
+ %shftphi = phi i64 [ %shft, %latch ]
+ br label %mergedexit
+
+mergedexit: ; preds = %latchexit, %headerexit
+ %retval = phi i64 [ %addphi, %headerexit ], [ %shftphi, %latchexit ]
+ ret i64 %retval
+}
+
+; mergedexit has edges from loop exit blocks and a block outside the loop.
+define void @test2(i1 %cond, i32 %n) {
+; CHECK-LABEL: header.1:
+; CHECK-NEXT: %add.iv.1 = add nuw nsw i64 %add.iv, 2
+; CHECK: br i1 %cmp1.1, label %latch.1, label %headerexit
+; CHECK-LABEL: latch.3:
+; CHECK: %cmp2.3 = icmp ult i64 %shft.3, %trip
+; CHECK-NEXT: br i1 %cmp2.3, label %header, label %latchexit, !llvm.loop
+entry:
+ br i1 %cond, label %preheader, label %mergedexit
+
+preheader: ; preds = %entry
+ %trip = zext i32 %n to i64
+ br label %header
+
+header: ; preds = %latch, %preheader
+ %iv = phi i64 [ 2, %preheader ], [ %add.iv, %latch ]
+ %add.iv = add nuw nsw i64 %iv, 2
+ %cmp1 = icmp ult i64 %add.iv, %trip
+ br i1 %cmp1, label %latch, label %headerexit
+
+latch: ; preds = %header
+ %shft = ashr i64 %add.iv, 1
+ %cmp2 = icmp ult i64 %shft, %trip
+ br i1 %cmp2, label %header, label %latchexit
+
+headerexit: ; preds = %header
+ br label %mergedexit
+
+latchexit: ; preds = %latch
+ br label %mergedexit
+
+mergedexit: ; preds = %latchexit, %headerexit, %entry
+ ret void
+}
+
+
+; exitsucc is from loop exit block only.
+define i64 @test3(i32 %n) {
+; CHECK-LABEL: test3(
+; CHECK-LABEL: headerexit:
+; CHECK-NEXT: br label %exitsucc
+; CHECK-LABEL: latchexit:
+; CHECK-NEXT: %shftphi = phi i64 [ %shft, %latch ], [ %shft.1, %latch.1 ], [ %shft.2, %latch.2 ], [ %shft.3, %latch.3 ]
+; CHECK-NEXT: ret i64 %shftphi
+; CHECK-LABEL: exitsucc:
+; CHECK-NEXT: ret i64 96
+entry:
+ br label %preheader
+
+preheader: ; preds = %bb
+ %trip = zext i32 %n to i64
+ br label %header
+
+header: ; preds = %latch, %preheader
+ %iv = phi i64 [ 2, %preheader ], [ %add.iv, %latch ]
+ %add.iv = add nuw nsw i64 %iv, 2
+ %cmp1 = icmp ult i64 %add.iv, %trip
+ br i1 %cmp1, label %latch, label %headerexit
+
+latch: ; preds = %header
+ %shft = ashr i64 %add.iv, 1
+ %cmp2 = icmp ult i64 %shft, %trip
+ br i1 %cmp2, label %header, label %latchexit
+
+headerexit: ; preds = %header
+ br label %exitsucc
+
+latchexit: ; preds = %latch
+ %shftphi = phi i64 [ %shft, %latch ]
+ ret i64 %shftphi
+
+exitsucc: ; preds = %headerexit
+ ret i64 96
+}
More information about the llvm-commits
mailing list