[PATCH] D68420: Fix PR40644: miscompile indexed FP constant store

[Thomas Preud'homme via Phabricator via llvm-commits]

thopre created this revision.
thopre added a reviewer: efriedma.
Herald added subscribers: arphaman, hiraditya.
Herald added a project: LLVM.

Functions replaceStoreOfFPConstant() and OptimizeFloatStore() both
replace store of float by a store of an integer unconditionally. However
this generates wrong code when the store that is replaced is an indexed
or truncating store. This commit solves this issue by adding an early
return in these functions when the store being considered is not a
normal store.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D68420

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp


Index: llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -419,6 +419,9 @@
 }
 
 SDValue SelectionDAGLegalize::OptimizeFloatStore(StoreSDNode* ST) {
+  if (!ISD::isNormalStore(ST))
+    return SDValue();
+
   LLVM_DEBUG(dbgs() << "Optimizing float store operations\n");
   // Turn 'store float 1.0, Ptr' -> 'store int 0x12345678, Ptr'
   // FIXME: We shouldn't do this for TargetConstantFP's.
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -15903,6 +15903,9 @@
   if (Value.getOpcode() == ISD::TargetConstantFP)
     return SDValue();
 
+  if (!ISD::isNormalStore(ST))
+    return SDValue();
+
   SDLoc DL(ST);
 
   SDValue Chain = ST->getChain();


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