[GlobalISel] Lower dbg.declare into indirect DBG_VALUE

Summary:
D31439 changed the semantics of dbg.declare to take the address of a
variable as the first argument, making it indirect.  It specifically
updated FastISel for this change here:

https://reviews.llvm.org/D31439#change-WVArzi177jPl

GlobalISel needs to follow suit, or else it will be missing a level of
indirection in the generated debuginfo.  This problem was seen in a Rust
debuginfo test on aarch64, since GlobalISel is used at -O0 for aarch64.

https://github.com/rust-lang/rust/issues/49807
https://bugzilla.redhat.com/show_bug.cgi?id=1611597
https://bugzilla.redhat.com/show_bug.cgi?id=1625768

Reviewers: dblaikie, aprantl, t.p.northover, javed.absar, rnk

Reviewed By: rnk

Subscribers: #debug-info, rovka, kristof.beyls, JDevlieghere, llvm-commits, tstellar

Differential Revision: https://reviews.llvm.org/D51749

llvm-svn: 341969

1 files changed, 6 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 974629bc4f4..f7b905c9db4 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -758,9 +758,12 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
       // instructions (in fact, they get ignored if they *do* exist).
       MF->setVariableDbgInfo(DI.getVariable(), DI.getExpression(),
                              getOrCreateFrameIndex(*AI), DI.getDebugLoc());
-    } else
-      MIRBuilder.buildDirectDbgValue(getOrCreateVReg(*Address),
-                                     DI.getVariable(), DI.getExpression());
+    } else {
+      // A dbg.declare describes the address of a source variable, so lower it
+      // into an indirect DBG_VALUE.
+      MIRBuilder.buildIndirectDbgValue(getOrCreateVReg(*Address),
+                                       DI.getVariable(), DI.getExpression());
+    }
     return true;
   }
   case Intrinsic::dbg_label: {