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Date:      Wed, 8 Sep 2021 18:16:28 GMT
From:      "Alfredo Dal'Ava Junior" <alfredo@FreeBSD.org>
To:        src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org
Subject:   git: d8199cf063f0 - stable/13 - llvm: Revert "[HardwareLoops] Change order of SCEV expression construction for InitLoopCount."
Message-ID:  <202109081816.188IGSQu008869@gitrepo.freebsd.org>

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The branch stable/13 has been updated by alfredo:

URL: https://cgit.FreeBSD.org/src/commit/?id=d8199cf063f055cd527767ff0bf2b01b3e598c9f

commit d8199cf063f055cd527767ff0bf2b01b3e598c9f
Author:     Alfredo Dal'Ava Junior <alfredo@FreeBSD.org>
AuthorDate: 2021-09-02 17:54:31 +0000
Commit:     Alfredo Dal'Ava Junior <alfredo@FreeBSD.org>
CommitDate: 2021-09-08 21:16:20 +0000

    llvm: Revert "[HardwareLoops] Change order of SCEV expression construction for InitLoopCount."
    
    Reverts llvm commit 42eaf4fe0adef3344adfd9fbccd49f325cb549ef, pointed
    from bisect as source of regression that causes liblzma to compress/
    uncompress incorrectly. It's know to affect powerpc64 BE only.
    
    The patch unbreaks FreeBSD powerpc64 installation media, since
    bsdinstall can't uncompress the *.txz produced by FreeBSD CI. It's
    probably miscompiling other software bas well.
    
    Upstream PR: https://bugs.llvm.org/show_bug.cgi?id=51714
    
    Reviewed by:    dim
    MFC after:      2 days
    Sponsored by:   Instituto de Pesquisas Eldorado (eldorado.org.br)
    Differential Revision:  https://reviews.freebsd.org/D31804
    
    (cherry picked from commit f21fcae487026987f44154de981c03b69efbc945)
---
 .../include/llvm/Analysis/TargetTransformInfo.h    |  1 +
 .../llvm/lib/Analysis/TargetTransformInfo.cpp      |  5 +----
 .../llvm/lib/CodeGen/HardwareLoops.cpp             | 26 +++++++++++++---------
 3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/contrib/llvm-project/llvm/include/llvm/Analysis/TargetTransformInfo.h b/contrib/llvm-project/llvm/include/llvm/Analysis/TargetTransformInfo.h
index cdfb04424e56..4dc442e1ed56 100644
--- a/contrib/llvm-project/llvm/include/llvm/Analysis/TargetTransformInfo.h
+++ b/contrib/llvm-project/llvm/include/llvm/Analysis/TargetTransformInfo.h
@@ -94,6 +94,7 @@ struct HardwareLoopInfo {
   Loop *L = nullptr;
   BasicBlock *ExitBlock = nullptr;
   BranchInst *ExitBranch = nullptr;
+  const SCEV *ExitCount = nullptr;
   const SCEV *TripCount = nullptr;
   IntegerType *CountType = nullptr;
   Value *LoopDecrement = nullptr; // Decrement the loop counter by this
diff --git a/contrib/llvm-project/llvm/lib/Analysis/TargetTransformInfo.cpp b/contrib/llvm-project/llvm/lib/Analysis/TargetTransformInfo.cpp
index e498401eb8b5..43cc90aedbc9 100644
--- a/contrib/llvm-project/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/contrib/llvm-project/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -217,10 +217,7 @@ bool HardwareLoopInfo::isHardwareLoopCandidate(ScalarEvolution &SE,
     // Note that this block may not be the loop latch block, even if the loop
     // has a latch block.
     ExitBlock = BB;
-    TripCount = SE.getAddExpr(EC, SE.getOne(EC->getType()));
-
-    if (!EC->getType()->isPointerTy() && EC->getType() != CountType)
-      TripCount = SE.getZeroExtendExpr(TripCount, CountType);
+    ExitCount = EC;
 
     break;
   }
diff --git a/contrib/llvm-project/llvm/lib/CodeGen/HardwareLoops.cpp b/contrib/llvm-project/llvm/lib/CodeGen/HardwareLoops.cpp
index 810b10c9c82a..354e50b4844d 100644
--- a/contrib/llvm-project/llvm/lib/CodeGen/HardwareLoops.cpp
+++ b/contrib/llvm-project/llvm/lib/CodeGen/HardwareLoops.cpp
@@ -187,7 +187,7 @@ namespace {
                  const DataLayout &DL,
                  OptimizationRemarkEmitter *ORE) :
       SE(SE), DL(DL), ORE(ORE), L(Info.L), M(L->getHeader()->getModule()),
-      TripCount(Info.TripCount),
+      ExitCount(Info.ExitCount),
       CountType(Info.CountType),
       ExitBranch(Info.ExitBranch),
       LoopDecrement(Info.LoopDecrement),
@@ -202,7 +202,7 @@ namespace {
     OptimizationRemarkEmitter *ORE = nullptr;
     Loop *L                 = nullptr;
     Module *M               = nullptr;
-    const SCEV *TripCount   = nullptr;
+    const SCEV *ExitCount   = nullptr;
     Type *CountType         = nullptr;
     BranchInst *ExitBranch  = nullptr;
     Value *LoopDecrement    = nullptr;
@@ -298,7 +298,7 @@ bool HardwareLoops::TryConvertLoop(HardwareLoopInfo &HWLoopInfo) {
   }
 
   assert(
-      (HWLoopInfo.ExitBlock && HWLoopInfo.ExitBranch && HWLoopInfo.TripCount) &&
+      (HWLoopInfo.ExitBlock && HWLoopInfo.ExitBranch && HWLoopInfo.ExitCount) &&
       "Hardware Loop must have set exit info.");
 
   BasicBlock *Preheader = L->getLoopPreheader();
@@ -384,12 +384,18 @@ Value *HardwareLoop::InitLoopCount() {
 
   SCEVExpander SCEVE(SE, DL, "loopcnt");
 
+  if (!ExitCount->getType()->isPointerTy() &&
+       ExitCount->getType() != CountType)
+    ExitCount = SE.getZeroExtendExpr(ExitCount, CountType);
+
+  ExitCount = SE.getAddExpr(ExitCount, SE.getOne(CountType));
+
   // If we're trying to use the 'test and set' form of the intrinsic, we need
   // to replace a conditional branch that is controlling entry to the loop. It
   // is likely (guaranteed?) that the preheader has an unconditional branch to
   // the loop header, so also check if it has a single predecessor.
-  if (SE.isLoopEntryGuardedByCond(L, ICmpInst::ICMP_NE, TripCount,
-                                  SE.getZero(TripCount->getType()))) {
+  if (SE.isLoopEntryGuardedByCond(L, ICmpInst::ICMP_NE, ExitCount,
+			          SE.getZero(ExitCount->getType()))) {
     LLVM_DEBUG(dbgs() << " - Attempting to use test.set counter.\n");
     UseLoopGuard |= ForceGuardLoopEntry;
   } else
@@ -401,19 +407,19 @@ Value *HardwareLoop::InitLoopCount() {
     BasicBlock *Predecessor = BB->getSinglePredecessor();
     // If it's not safe to create a while loop then don't force it and create a
     // do-while loop instead
-    if (!isSafeToExpandAt(TripCount, Predecessor->getTerminator(), SE))
+    if (!isSafeToExpandAt(ExitCount, Predecessor->getTerminator(), SE))
         UseLoopGuard = false;
     else
         BB = Predecessor;
   }
 
-  if (!isSafeToExpandAt(TripCount, BB->getTerminator(), SE)) {
-    LLVM_DEBUG(dbgs() << "- Bailing, unsafe to expand TripCount "
-               << *TripCount << "\n");
+  if (!isSafeToExpandAt(ExitCount, BB->getTerminator(), SE)) {
+    LLVM_DEBUG(dbgs() << "- Bailing, unsafe to expand ExitCount "
+               << *ExitCount << "\n");
     return nullptr;
   }
 
-  Value *Count = SCEVE.expandCodeFor(TripCount, CountType,
+  Value *Count = SCEVE.expandCodeFor(ExitCount, CountType,
                                      BB->getTerminator());
 
   // FIXME: We've expanded Count where we hope to insert the counter setting



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