[llvm] 423da61 - [runtime-unroll] Inline canSafelyUnrollMultiExitLoop [NFC]

[Philip Reames via llvm-commits]

Author: Philip Reames
Date: 2021-11-15T11:39:07-08:00
New Revision: 423da618354aa31ebc80681ad9ad71ddf6b0fcfd

URL: https://github.com/llvm/llvm-project/commit/423da618354aa31ebc80681ad9ad71ddf6b0fcfd
DIFF: https://github.com/llvm/llvm-project/commit/423da618354aa31ebc80681ad9ad71ddf6b0fcfd.diff

LOG: [runtime-unroll] Inline canSafelyUnrollMultiExitLoop [NFC]

All of the interesting logic from this routine has been removed, inline the single check into the sole non-assert caller.  The assert use has little value with the restructured code and is simply dropped.

Added: 
    

Modified: 
    llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
index 34d87bbcd751..aca25bed78b0 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -411,35 +411,11 @@ CloneLoopBlocks(Loop *L, Value *NewIter, const bool UseEpilogRemainder,
   return NewLoop;
 }
 
-/// Returns true if we can safely unroll a multi-exit/exiting loop. OtherExits
-/// is populated with all the loop exit blocks other than the LatchExit block.
-static bool canSafelyUnrollMultiExitLoop(Loop *L, BasicBlock *LatchExit,
-                                         bool PreserveLCSSA,
-                                         bool UseEpilogRemainder) {
-
-  // We currently have some correctness constrains in unrolling a multi-exit
-  // loop. Check for these below.
-
-  // We rely on LCSSA form being preserved when the exit blocks are transformed.
-  // (Note that only an off-by-default mode of the old PM disables PreserveLCCA.)
-  if (!PreserveLCSSA)
-    return false;
-
-  // All constraints have been satisfied.
-  return true;
-}
-
 /// Returns true if we can profitably unroll the multi-exit loop L. Currently,
 /// we return true only if UnrollRuntimeMultiExit is set to true.
 static bool canProfitablyUnrollMultiExitLoop(
     Loop *L, SmallVectorImpl<BasicBlock *> &OtherExits, BasicBlock *LatchExit,
-    bool PreserveLCSSA, bool UseEpilogRemainder) {
-
-#if !defined(NDEBUG)
-  assert(canSafelyUnrollMultiExitLoop(L, LatchExit, PreserveLCSSA,
-                                      UseEpilogRemainder) &&
-         "Should be safe to unroll before checking profitability!");
-#endif
+    bool UseEpilogRemainder) {
 
   // Priority goes to UnrollRuntimeMultiExit if it's supplied.
   if (UnrollRuntimeMultiExit.getNumOccurrences())
@@ -638,12 +614,13 @@ bool llvm::UnrollRuntimeLoopRemainder(
   // Support only single exit and exiting block unless multi-exit loop
   // unrolling is enabled.
   if (!L->getExitingBlock() || OtherExits.size()) {
-    if (!canSafelyUnrollMultiExitLoop(L, LatchExit, PreserveLCSSA,
-                                      UseEpilogRemainder))
+    // We rely on LCSSA form being preserved when the exit blocks are transformed.
+    // (Note that only an off-by-default mode of the old PM disables PreserveLCCA.)
+    if (!PreserveLCSSA)
       return false;
 
     if (!canProfitablyUnrollMultiExitLoop(L, OtherExits, LatchExit,
-                                          PreserveLCSSA, UseEpilogRemainder)) {
+                                          UseEpilogRemainder)) {
       LLVM_DEBUG(
           dbgs()
           << "Multiple exit/exiting blocks in loop and multi-exit unrolling not "