[PATCH] D49454: [DebugInfo] LowerDbgDeclare: Add derefs when handling CallInst users

[Vedant Kumar via Phabricator via llvm-commits]

vsk added inline comments.


================
Comment at: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp:4965-4971
   if (auto *FISDN = dyn_cast<FrameIndexSDNode>(N.getNode())) {
     // Construct a FrameIndexDbgValue for FrameIndexSDNodes so we can describe
     // stack slot locations as such instead of as indirectly addressed
     // locations.
-    return DAG.getFrameIndexDbgValue(Variable, Expr, FISDN->getIndex(), dl,
-                                     DbgSDNodeOrder);
+    return DAG.getFrameIndexDbgValue(Variable, Expr, FISDN->getIndex(),
+                                     /*IsIndirect*/ false, dl, DbgSDNodeOrder);
   }
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rnk wrote:
> So, this should only be called in the case where the value of the variable is the address of some stack location, i.e. `int x = 0; int *px = &x;`, after optimization, we'll have this direct frame index dbg.value for px. I think that source fragment in a comment would help clarify why IsIndirect is false.
Isn't there one more case, where the value of the variable lives inside of some stack location?

To build on your example, I think the case you described looks like this:

  dbg.value(i32* %px, !"int *px", !DIExpression())

And the one I'm pointing out looks like this:

  dbg.value(i32* %px, !"int x", !DIExpression(DW_OP_deref))


https://reviews.llvm.org/D49454