[llvm] 664e1da - [LoopLoadElim] Make sure all loops are in simplify form. PR48150

[Max Kazantsev via llvm-commits]

Author: Max Kazantsev
Date: 2020-11-26T10:51:11+07:00
New Revision: 664e1da485d244325947d056a271c3c733ad4c7c

URL: https://github.com/llvm/llvm-project/commit/664e1da485d244325947d056a271c3c733ad4c7c
DIFF: https://github.com/llvm/llvm-project/commit/664e1da485d244325947d056a271c3c733ad4c7c.diff

LOG: [LoopLoadElim] Make sure all loops are in simplify form. PR48150

LoopLoadElim may end up expanding an AddRec from a loop
which is not the current loop. This loop may not be in simplify
form. We figure it out after the no-return point, so cannot bail
in this case.

AddRec requires simplify form to expand. The only way to ensure
this does not crash is to simplify all loops beforehand.

The issue only exists in new PM. Old PM requests LoopSimplify
required pass and it simplifies all loops before the opt begins.

Differential Revision: https://reviews.llvm.org/D91525
Reviewed By: asbirlea, aeubanks

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
    llvm/test/Transforms/LoopLoadElim/pr-48150.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp b/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
index 74e32fb870b5..475448740ae4 100644
--- a/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
@@ -56,6 +56,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils.h"
+#include "llvm/Transforms/Utils/LoopSimplify.h"
 #include "llvm/Transforms/Utils/LoopVersioning.h"
 #include "llvm/Transforms/Utils/ScalarEvolutionExpander.h"
 #include "llvm/Transforms/Utils/SizeOpts.h"
@@ -610,6 +611,7 @@ class LoadEliminationForLoop {
 static bool
 eliminateLoadsAcrossLoops(Function &F, LoopInfo &LI, DominatorTree &DT,
                           BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI,
+                          ScalarEvolution *SE, AssumptionCache *AC,
                           function_ref<const LoopAccessInfo &(Loop &)> GetLAI) {
   // Build up a worklist of inner-loops to transform to avoid iterator
   // invalidation.
@@ -618,14 +620,17 @@ eliminateLoadsAcrossLoops(Function &F, LoopInfo &LI, DominatorTree &DT,
   // which merely optimizes the use of loads in a loop.
   SmallVector<Loop *, 8> Worklist;
 
+  bool Changed = false;
+
   for (Loop *TopLevelLoop : LI)
-    for (Loop *L : depth_first(TopLevelLoop))
+    for (Loop *L : depth_first(TopLevelLoop)) {
+      Changed |= simplifyLoop(L, &DT, &LI, SE, AC, /*MSSAU*/ nullptr, false);
       // We only handle inner-most loops.
       if (L->isInnermost())
         Worklist.push_back(L);
+    }
 
   // Now walk the identified inner loops.
-  bool Changed = false;
   for (Loop *L : Worklist) {
     // The actual work is performed by LoadEliminationForLoop.
     LoadEliminationForLoop LEL(L, &LI, GetLAI(*L), &DT, BFI, PSI);
@@ -660,7 +665,7 @@ class LoopLoadElimination : public FunctionPass {
 
     // Process each loop nest in the function.
     return eliminateLoadsAcrossLoops(
-        F, LI, DT, BFI, PSI,
+        F, LI, DT, BFI, PSI, /*SE*/ nullptr, /*AC*/ nullptr,
         [&LAA](Loop &L) -> const LoopAccessInfo & { return LAA.getInfo(&L); });
   }
 
@@ -717,7 +722,7 @@ PreservedAnalyses LoopLoadEliminationPass::run(Function &F,
 
   auto &LAM = AM.getResult<LoopAnalysisManagerFunctionProxy>(F).getManager();
   bool Changed = eliminateLoadsAcrossLoops(
-      F, LI, DT, BFI, PSI, [&](Loop &L) -> const LoopAccessInfo & {
+      F, LI, DT, BFI, PSI, &SE, &AC, [&](Loop &L) -> const LoopAccessInfo & {
         LoopStandardAnalysisResults AR = {AA,  AC,  DT,      LI,  SE,
                                           TLI, TTI, nullptr, MSSA};
         return LAM.getResult<LoopAccessAnalysis>(L, AR);

diff  --git a/llvm/test/Transforms/LoopLoadElim/pr-48150.ll b/llvm/test/Transforms/LoopLoadElim/pr-48150.ll
index 60cc02c50ad4..a88fd9b9d938 100644
--- a/llvm/test/Transforms/LoopLoadElim/pr-48150.ll
+++ b/llvm/test/Transforms/LoopLoadElim/pr-48150.ll
@@ -1,6 +1,4 @@
 ; RUN: opt -passes=loop-load-elim -S < %s | FileCheck %s
-; REQUIRES: asserts
-; XFAIL: *
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128-ni:1-p2:32:8:8:32-ni:2"
 target triple = "x86_64-unknown-linux-gnu"