[llvm] r320421 - Revert r320407 "[InstCombine] Fix PR35618: Instcombine hangs on single minmax load bitcast."

[Hans Wennborg via llvm-commits]

Author: hans
Date: Mon Dec 11 13:15:27 2017
New Revision: 320421

URL: http://llvm.org/viewvc/llvm-project?rev=320421&view=rev
Log:
Revert r320407 "[InstCombine] Fix PR35618: Instcombine hangs on single minmax load bitcast."

The tests fail (opt asserts) on Windows.

> Summary:
> If we have pattern `store (load(bitcast(select (cmp(V1, V2), &V1,
> &V2)))), bitcast)`, but the load is used in other instructions, it leads
> to looping in InstCombiner. Patch adds additional check that all users
> of the load instructions are stores and then replaces all uses of load
> instruction by the new one with new type.
>
> Reviewers: RKSimon, spatel, majnemer
>
> Subscribers: llvm-commits
>
> Differential Revision: https://reviews.llvm.org/D41072

Removed:
    llvm/trunk/test/Transforms/InstCombine/multiple-uses-load-bitcast-select.ll
Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp?rev=320421&r1=320420&r2=320421&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp Mon Dec 11 13:15:27 2017
@@ -1344,24 +1344,9 @@ bool removeBitcastsFromLoadStoreOnMinMax
   if (!isMinMaxWithLoads(LoadAddr))
     return false;
 
-  if (!all_of(LI->users(), [LI](User *U) {
-        auto *SI = dyn_cast<StoreInst>(U);
-        return SI && SI->getPointerOperand() != LI &&
-               !SI->getPointerOperand()->isSwiftError();
-      }))
-    return false;
-
-  IC.Builder.SetInsertPoint(LI);
   LoadInst *NewLI = combineLoadToNewType(
       IC, *LI, LoadAddr->getType()->getPointerElementType());
-  // Replace all the stores with stores of the newly loaded value.
-  for (auto *UI : LI->users()) {
-    auto *SI = cast<StoreInst>(UI);
-    IC.Builder.SetInsertPoint(SI);
-    combineStoreToNewValue(IC, *SI, NewLI);
-    IC.eraseInstFromFunction(*SI);
-  }
-  IC.eraseInstFromFunction(*LI);
+  combineStoreToNewValue(IC, SI, NewLI);
   return true;
 }
 
@@ -1390,7 +1375,7 @@ Instruction *InstCombiner::visitStoreIns
     return eraseInstFromFunction(SI);
 
   if (removeBitcastsFromLoadStoreOnMinMax(*this, SI))
-    return nullptr;
+    return eraseInstFromFunction(SI);
 
   // Replace GEP indices if possible.
   if (Instruction *NewGEPI = replaceGEPIdxWithZero(*this, Ptr, SI)) {

Removed: llvm/trunk/test/Transforms/InstCombine/multiple-uses-load-bitcast-select.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/multiple-uses-load-bitcast-select.ll?rev=320420&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/multiple-uses-load-bitcast-select.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/multiple-uses-load-bitcast-select.ll (removed)
@@ -1,30 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -instcombine -S -data-layout="E-m:e-i1:8:16-i8:8:16-i64:64-f128:64-v128:64-a:8:16-n32:64" | FileCheck %s
-
-define void @PR35618(i64* %st1, double* %st2) {
-; CHECK-LABEL: @PR35618(
-; CHECK-NEXT:    [[Y1:%.*]] = alloca double, align 8
-; CHECK-NEXT:    [[Z1:%.*]] = alloca double, align 8
-; CHECK-NEXT:    [[LD1:%.*]] = load double, double* [[Y1]], align 8
-; CHECK-NEXT:    [[LD2:%.*]] = load double, double* [[Z1]], align 8
-; CHECK-NEXT:    [[TMP10:%.*]] = fcmp olt double [[LD1]], [[LD2]]
-; CHECK-NEXT:    [[TMP121:%.*]] = select i1 [[TMP10]], double [[LD1]], double [[LD2]]
-; CHECK-NEXT:    [[TMP1:%.*]] = bitcast i64* [[ST1:%.*]] to double*
-; CHECK-NEXT:    store double [[TMP121]], double* [[TMP1]], align 8
-; CHECK-NEXT:    store double [[TMP121]], double* [[ST2:%.*]], align 8
-; CHECK-NEXT:    ret void
-;
-  %y1 = alloca double
-  %z1 = alloca double
-  %ld1 = load double, double* %y1
-  %ld2 = load double, double* %z1
-  %tmp10 = fcmp olt double %ld1, %ld2
-  %sel = select i1 %tmp10, double* %y1, double* %z1
-  %tmp11 = bitcast double* %sel to i64*
-  %tmp12 = load i64, i64* %tmp11
-  store i64 %tmp12, i64* %st1
-  %bc = bitcast double* %st2 to i64*
-  store i64 %tmp12, i64* %bc
-  ret void
-}
-