[llvm] [SROA] Fix debug locations for variables with non-zero offsets (PR #97750)

[Orlando Cazalet-Hyams via llvm-commits]

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@@ -4967,46 +4967,224 @@ AllocaInst *SROA::rewritePartition(AllocaInst &AI, AllocaSlices &AS,
   return NewAI;
 }
 
-static void insertNewDbgInst(DIBuilder &DIB, DbgDeclareInst *Orig,
-                             AllocaInst *NewAddr, DIExpression *NewFragmentExpr,
-                             Instruction *BeforeInst) {
-  DIB.insertDeclare(NewAddr, Orig->getVariable(), NewFragmentExpr,
+// There isn't a shared interface to get the "address" parts out of a
+// dbg.declare and dbg.assign, so provide some wrappers now for
+// both debug intrinsics and records.
+const Value *getAddress(const DbgVariableIntrinsic *DVI) {
+  if (const auto *DAI = dyn_cast<DbgAssignIntrinsic>(DVI))
+    return DAI->getAddress();
+  return cast<DbgDeclareInst>(DVI)->getAddress();
+}
+const Value *getAddress(const DbgVariableRecord *DVR) {
+  assert(DVR->getType() == DbgVariableRecord::LocationType::Declare ||
+         DVR->getType() == DbgVariableRecord::LocationType::Assign);
+  return DVR->getAddress();
+}
+bool isKillAddress(const DbgVariableIntrinsic *DVI) {
+  if (const auto *DAI = dyn_cast<DbgAssignIntrinsic>(DVI))
+    return DAI->isKillAddress();
+  return cast<DbgDeclareInst>(DVI)->isKillLocation();
+}
+bool isKillAddress(const DbgVariableRecord *DVR) {
+  assert(DVR->getType() == DbgVariableRecord::LocationType::Declare ||
+         DVR->getType() == DbgVariableRecord::LocationType::Assign);
+  if (DVR->getType() == DbgVariableRecord::LocationType::Assign)
+    return DVR->isKillAddress();
+  return DVR->isKillLocation();
+}
+const DIExpression *getAddressExpression(const DbgVariableIntrinsic *DVI) {
+  if (const auto *DAI = dyn_cast<DbgAssignIntrinsic>(DVI))
+    return DAI->getAddressExpression();
+  return cast<DbgDeclareInst>(DVI)->getExpression();
+}
+const DIExpression *getAddressExpression(const DbgVariableRecord *DVR) {
+  assert(DVR->getType() == DbgVariableRecord::LocationType::Declare ||
+         DVR->getType() == DbgVariableRecord::LocationType::Assign);
+  if (DVR->getType() == DbgVariableRecord::LocationType::Assign)
+    return DVR->getAddressExpression();
+  return DVR->getExpression();
+}
+
+/// Similar to DIExpression::createFragmentExpression except for 3 important
+/// distinctions:
+///   1. The new fragment isn't relative to an existing fragment.
+///   2. There are no checks on the the operation types because it is assumed
+///      the location this expression is computing is not implicit (i.e., it's
+///      always safe to create a fragment because arithmetic operations apply
+///      to the address computation, not to an implicit value computation).
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OCHyams wrote:

Sorry yep that was a jumble. Is this better? If not I'm happy to trim it down to your suggestion.

https://github.com/llvm/llvm-project/pull/97750