[llvm-commits] [llvm] r137190 - in /llvm/trunk: include/llvm/Analysis/LoopInfo.h lib/Transforms/Utils/LoopUnroll.cpp test/Transforms/LoopUnroll/2011-08-08-PhiUpdate.ll test/Transforms/LoopUnroll/2011-08-09-PhiUpdate.ll
Andrew Trick
atrick at apple.com
Tue Aug 9 17:28:10 PDT 2011
Author: atrick
Date: Tue Aug 9 19:28:10 2011
New Revision: 137190
URL: http://llvm.org/viewvc/llvm-project?rev=137190&view=rev
Log:
Fix the LoopUnroller to handle nontrivial loops and partial unrolling.
These are not individual bug fixes. I had to rewrite a good chunk of
the unroller to make it sane. I think it was getting lucky on trivial
completely unrolled loops with no early exits. I included some fairly
simple unit tests for partial unrolling. I didn't do much stress
testing, so it may not be perfect, but should be usable now.
Added:
llvm/trunk/test/Transforms/LoopUnroll/2011-08-08-PhiUpdate.ll
llvm/trunk/test/Transforms/LoopUnroll/2011-08-09-PhiUpdate.ll
Modified:
llvm/trunk/include/llvm/Analysis/LoopInfo.h
llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp
Modified: llvm/trunk/include/llvm/Analysis/LoopInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/LoopInfo.h?rev=137190&r1=137189&r2=137190&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/LoopInfo.h (original)
+++ llvm/trunk/include/llvm/Analysis/LoopInfo.h Tue Aug 9 19:28:10 2011
@@ -134,6 +134,11 @@
block_iterator block_begin() const { return Blocks.begin(); }
block_iterator block_end() const { return Blocks.end(); }
+ /// getNumBlocks - Get the number of blocks in this loop.
+ unsigned getNumBlocks() const {
+ return std::distance(block_begin(), block_end());
+ }
+
/// isLoopExiting - True if terminator in the block can branch to another
/// block that is outside of the current loop.
///
Modified: llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp?rev=137190&r1=137189&r2=137190&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp Tue Aug 9 19:28:10 2011
@@ -21,6 +21,7 @@
#include "llvm/BasicBlock.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/LoopIterator.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Support/Debug.h"
@@ -225,11 +226,25 @@
Headers.push_back(Header);
Latches.push_back(LatchBlock);
+ // The current on-the-fly SSA update requires blocks to be processed in
+ // reverse postorder so that LastValueMap contains the correct value at each
+ // exit.
+ LoopBlocksDFS DFS(L);
+ {
+ // Traverse the loop blocks using depth-first search to record RPO numbers
+ // for each block in the DFS result.
+ LoopBlocksTraversal Traversal(DFS, LI);
+ for (LoopBlocksTraversal::POTIterator POI = Traversal.begin(),
+ POE = Traversal.end(); POI != POE; ++POI);
+ }
+ // Stash the DFS iterators before adding blocks to the loop.
+ LoopBlocksDFS::RPOIterator BlockBegin = DFS.beginRPO();
+ LoopBlocksDFS::RPOIterator BlockEnd = DFS.endRPO();
+
for (unsigned It = 1; It != Count; ++It) {
std::vector<BasicBlock*> NewBlocks;
- for (std::vector<BasicBlock*>::iterator BB = LoopBlocks.begin(),
- E = LoopBlocks.end(); BB != E; ++BB) {
+ for (LoopBlocksDFS::RPOIterator BB = BlockBegin; BB != BlockEnd; ++BB) {
ValueToValueMapTy VMap;
BasicBlock *New = CloneBasicBlock(*BB, VMap, "." + Twine(It));
Header->getParent()->getBasicBlockList().push_back(New);
@@ -255,35 +270,27 @@
L->addBasicBlockToLoop(New, LI->getBase());
- // Add phi entries for newly created values to all exit blocks except
- // the successor of the latch block. The successor of the exit block will
- // be updated specially after unrolling all the way.
- if (*BB != LatchBlock)
- for (succ_iterator SI = succ_begin(*BB), SE = succ_end(*BB); SI != SE;
- ++SI)
- if (!L->contains(*SI))
- for (BasicBlock::iterator BBI = (*SI)->begin();
- PHINode *phi = dyn_cast<PHINode>(BBI); ++BBI) {
- Value *Incoming = phi->getIncomingValueForBlock(*BB);
- phi->addIncoming(Incoming, New);
- }
-
+ // Add phi entries for newly created values to all exit blocks.
+ for (succ_iterator SI = succ_begin(*BB), SE = succ_end(*BB);
+ SI != SE; ++SI) {
+ if (L->contains(*SI))
+ continue;
+ for (BasicBlock::iterator BBI = (*SI)->begin();
+ PHINode *phi = dyn_cast<PHINode>(BBI); ++BBI) {
+ Value *Incoming = phi->getIncomingValueForBlock(*BB);
+ ValueToValueMapTy::iterator It = LastValueMap.find(Incoming);
+ if (It != LastValueMap.end())
+ Incoming = It->second;
+ phi->addIncoming(Incoming, New);
+ }
+ }
// Keep track of new headers and latches as we create them, so that
// we can insert the proper branches later.
if (*BB == Header)
Headers.push_back(New);
- if (*BB == LatchBlock) {
+ if (*BB == LatchBlock)
Latches.push_back(New);
- // Also, clear out the new latch's back edge so that it doesn't look
- // like a new loop, so that it's amenable to being merged with adjacent
- // blocks later on.
- TerminatorInst *Term = New->getTerminator();
- assert(L->contains(Term->getSuccessor(!ContinueOnTrue)));
- assert(Term->getSuccessor(ContinueOnTrue) == LoopExit);
- Term->setSuccessor(!ContinueOnTrue, NULL);
- }
-
NewBlocks.push_back(New);
}
@@ -294,36 +301,24 @@
::RemapInstruction(I, LastValueMap);
}
- // The latch block exits the loop. If there are any PHI nodes in the
- // successor blocks, update them to use the appropriate values computed as the
- // last iteration of the loop.
- if (Count != 1) {
- BasicBlock *LastIterationBB = cast<BasicBlock>(LastValueMap[LatchBlock]);
- for (succ_iterator SI = succ_begin(LatchBlock), SE = succ_end(LatchBlock);
- SI != SE; ++SI) {
- for (BasicBlock::iterator BBI = (*SI)->begin();
- PHINode *PN = dyn_cast<PHINode>(BBI); ++BBI) {
- Value *InVal = PN->removeIncomingValue(LatchBlock, false);
- // If this value was defined in the loop, take the value defined by the
- // last iteration of the loop.
- if (Instruction *InValI = dyn_cast<Instruction>(InVal)) {
- if (L->contains(InValI))
- InVal = LastValueMap[InVal];
- }
- PN->addIncoming(InVal, LastIterationBB);
- }
- }
- }
-
- // Now, if we're doing complete unrolling, loop over the PHI nodes in the
- // original block, setting them to their incoming values.
- if (CompletelyUnroll) {
- BasicBlock *Preheader = L->getLoopPreheader();
- for (unsigned i = 0, e = OrigPHINode.size(); i != e; ++i) {
- PHINode *PN = OrigPHINode[i];
+ // Loop over the PHI nodes in the original block, setting incoming values.
+ for (unsigned i = 0, e = OrigPHINode.size(); i != e; ++i) {
+ PHINode *PN = OrigPHINode[i];
+ if (CompletelyUnroll) {
PN->replaceAllUsesWith(PN->getIncomingValueForBlock(Preheader));
Header->getInstList().erase(PN);
}
+ else if (Count > 1) {
+ Value *InVal = PN->removeIncomingValue(LatchBlock, false);
+ // If this value was defined in the loop, take the value defined by the
+ // last iteration of the loop.
+ if (Instruction *InValI = dyn_cast<Instruction>(InVal)) {
+ if (L->contains(InValI))
+ InVal = LastValueMap[InVal];
+ }
+ assert(Latches.back() == LastValueMap[LatchBlock] && "bad last latch");
+ PN->addIncoming(InVal, Latches.back());
+ }
}
// Now that all the basic blocks for the unrolled iterations are in place,
@@ -355,6 +350,19 @@
// iteration.
Term->setSuccessor(!ContinueOnTrue, Dest);
} else {
+ // Remove phi operands at this loop exit
+ if (Dest != LoopExit) {
+ BasicBlock *BB = Latches[i];
+ for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
+ SI != SE; ++SI) {
+ if (*SI == Headers[i])
+ continue;
+ for (BasicBlock::iterator BBI = (*SI)->begin();
+ PHINode *Phi = dyn_cast<PHINode>(BBI); ++BBI) {
+ Phi->removeIncomingValue(BB, false);
+ }
+ }
+ }
// Replace the conditional branch with an unconditional one.
BranchInst::Create(Dest, Term);
Term->eraseFromParent();
Added: llvm/trunk/test/Transforms/LoopUnroll/2011-08-08-PhiUpdate.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/2011-08-08-PhiUpdate.ll?rev=137190&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/2011-08-08-PhiUpdate.ll (added)
+++ llvm/trunk/test/Transforms/LoopUnroll/2011-08-08-PhiUpdate.ll Tue Aug 9 19:28:10 2011
@@ -0,0 +1,100 @@
+; RUN: opt < %s -loop-unroll -S -unroll-count=4 | FileCheck %s
+; Test phi update after partial unroll.
+
+declare i1 @check() nounwind
+
+; CHECK: @test
+; CHECK: if.else:
+; CHECK: if.then.loopexit
+; CHECK: %sub5.lcssa = phi i32 [ %sub{{.*}}, %if.else{{.*}} ], [ %sub{{.*}}, %if.else{{.*}} ], [ %sub{{.*}}, %if.else{{.*}} ], [ %sub{{.*}}, %if.else{{.*}} ]
+; CHECK: if.else.3
+define void @test1(i32 %i, i32 %j) nounwind uwtable ssp {
+entry:
+ %cond1 = call zeroext i1 @check()
+ br i1 %cond1, label %if.then, label %if.else.lr.ph
+
+if.else.lr.ph: ; preds = %entry
+ br label %if.else
+
+if.else: ; preds = %if.else, %if.else.lr.ph
+ %sub = phi i32 [ %i, %if.else.lr.ph ], [ %sub5, %if.else ]
+ %sub5 = sub i32 %sub, %j
+ %cond2 = call zeroext i1 @check()
+ br i1 %cond2, label %if.then, label %if.else
+
+if.then: ; preds = %if.else, %entry
+ %i.tr = phi i32 [ %i, %entry ], [ %sub5, %if.else ]
+ ret void
+
+}
+
+; PR7318: assertion failure after doing a simple loop unroll
+;
+; CHECK: @test2
+; CHECK: bb1.bb2_crit_edge:
+; CHECK: %.lcssa = phi i32 [ %{{[2468]}}, %bb1{{.*}} ], [ %{{[2468]}}, %bb1{{.*}} ], [ %{{[2468]}}, %bb1{{.*}} ], [ %{{[2468]}}, %bb1{{.*}} ]
+; CHECK: bb1.3:
+define i32 @test2(i32* nocapture %p, i32 %n) nounwind readonly {
+entry:
+ %0 = icmp sgt i32 %n, 0 ; <i1> [#uses=1]
+ br i1 %0, label %bb.nph, label %bb2
+
+bb.nph: ; preds = %entry
+ %tmp = zext i32 %n to i64 ; <i64> [#uses=1]
+ br label %bb
+
+bb: ; preds = %bb.nph, %bb1
+ %indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %bb1 ] ; <i64> [#uses=2]
+ %s.01 = phi i32 [ 0, %bb.nph ], [ %2, %bb1 ] ; <i32> [#uses=1]
+ %scevgep = getelementptr i32* %p, i64 %indvar ; <i32*> [#uses=1]
+ %1 = load i32* %scevgep, align 1 ; <i32> [#uses=1]
+ %2 = add nsw i32 %1, %s.01 ; <i32> [#uses=2]
+ br label %bb1
+
+bb1: ; preds = %bb
+ %indvar.next = add i64 %indvar, 1 ; <i64> [#uses=2]
+ %exitcond = icmp ne i64 %indvar.next, %tmp ; <i1> [#uses=1]
+ br i1 %exitcond, label %bb, label %bb1.bb2_crit_edge
+
+bb1.bb2_crit_edge: ; preds = %bb1
+ %.lcssa = phi i32 [ %2, %bb1 ] ; <i32> [#uses=1]
+ br label %bb2
+
+bb2: ; preds = %bb1.bb2_crit_edge, %entry
+ %s.0.lcssa = phi i32 [ %.lcssa, %bb1.bb2_crit_edge ], [ 0, %entry ] ; <i32> [#uses=1]
+ ret i32 %s.0.lcssa
+}
+
+; Check phi update for loop with an early-exit.
+;
+; CHECK: @test3
+; CHECK: return.loopexit:
+; CHECK: %tmp7.i.lcssa = phi i32 [ %tmp7.i{{.*}}, %land.lhs.true{{.*}} ], [ %tmp7.i{{.*}}, %land.lhs.true{{.*}} ], [ %tmp7.i{{.*}}, %land.lhs.true{{.*}} ], [ %tmp7.i{{.*}}, %land.lhs.true{{.*}} ]
+; CHECK: exit.3:
+define i32 @test3() nounwind uwtable ssp align 2 {
+entry:
+ br i1 undef, label %return, label %if.end
+
+if.end: ; preds = %entry
+ br label %do.body
+
+do.body: ; preds = %do.cond, %if.end
+ br i1 undef, label %exit, label %do.cond
+
+exit: ; preds = %do.body
+ %tmp7.i = load i32* undef, align 8
+ br i1 undef, label %do.cond, label %land.lhs.true
+
+land.lhs.true: ; preds = %exit
+ br i1 undef, label %return, label %do.cond
+
+do.cond: ; preds = %land.lhs.true, %exit, %do.body
+ br i1 undef, label %do.end, label %do.body
+
+do.end: ; preds = %do.cond
+ br label %return
+
+return: ; preds = %do.end, %land.lhs.true, %entry
+ %retval.0 = phi i32 [ 0, %do.end ], [ 0, %entry ], [ %tmp7.i, %land.lhs.true ]
+ ret i32 %retval.0
+}
Added: llvm/trunk/test/Transforms/LoopUnroll/2011-08-09-PhiUpdate.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/2011-08-09-PhiUpdate.ll?rev=137190&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/2011-08-09-PhiUpdate.ll (added)
+++ llvm/trunk/test/Transforms/LoopUnroll/2011-08-09-PhiUpdate.ll Tue Aug 9 19:28:10 2011
@@ -0,0 +1,62 @@
+; RUN: opt -S < %s -instcombine -inline -jump-threading -loop-unroll -unroll-count=4 | FileCheck %s
+;
+; This is a test case that required a number of setup passes because
+; it depends on block order.
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-macosx10.6.8"
+
+declare i1 @check() nounwind
+declare i32 @getval() nounwind
+
+; Check that the loop exit merges values from all the iterations. This
+; could be a tad fragile, but it's a good test.
+;
+; CHECK: @foo
+; CHECK: return:
+; CHECK: %retval.0 = phi i32 [ %tmp7.i, %land.lhs.true ], [ 0, %do.cond ], [ %tmp7.i.1, %land.lhs.true.1 ], [ 0, %do.cond.1 ], [ %tmp7.i.2, %land.lhs.true.2 ], [ 0, %do.cond.2 ], [ %tmp7.i.3, %land.lhs.true.3 ], [ 0, %do.cond.3 ]
+; CHECK-NOT: @bar
+; CHECK: bar.exit.3
+define i32 @foo() uwtable ssp align 2 {
+entry:
+ br i1 undef, label %return, label %if.end
+
+if.end: ; preds = %entry
+ %call2 = call i32 @getval()
+ br label %do.body
+
+do.body: ; preds = %do.cond, %if.end
+ %call6 = call i32 @bar()
+ %cmp = icmp ne i32 %call6, 0
+ br i1 %cmp, label %land.lhs.true, label %do.cond
+
+land.lhs.true: ; preds = %do.body
+ %call10 = call i32 @getval()
+ %cmp11 = icmp eq i32 0, %call10
+ br i1 %cmp11, label %return, label %do.cond
+
+do.cond: ; preds = %land.lhs.true, %do.body
+ %cmp18 = icmp sle i32 0, %call2
+ br i1 %cmp18, label %do.body, label %return
+
+return: ; preds = %do.cond, %land.lhs.true, %entry
+ %retval.0 = phi i32 [ 0, %entry ], [ %call6, %land.lhs.true ], [ 0, %do.cond ]
+ ret i32 %retval.0
+}
+
+define linkonce_odr i32 @bar() nounwind uwtable ssp align 2 {
+entry:
+ br i1 undef, label %land.lhs.true, label %cond.end
+
+land.lhs.true: ; preds = %entry
+ %cmp4 = call zeroext i1 @check()
+ br i1 %cmp4, label %cond.true, label %cond.end
+
+cond.true: ; preds = %land.lhs.true
+ %tmp7 = call i32 @getval()
+ br label %cond.end
+
+cond.end: ; preds = %cond.true, %land.lhs.true, %entry
+ %cond = phi i32 [ %tmp7, %cond.true ], [ 0, %land.lhs.true ], [ 0, %entry ]
+ ret i32 %cond
+}
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