From: Ahmed Bougacha <ahmed.bougacha@gmail.com>
Date: Tue, 7 Mar 2017 20:34:20 +0000 (+0000)
Subject: [GlobalISel] Emit DBG_VALUE %noreg for non-int/fp constant values.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e8bbfecd516ec25ac0dd91c30ff1b660ae05c326;p=llvm

[GlobalISel] Emit DBG_VALUE %noreg for non-int/fp constant values.

When a dbg_value has a constant operand that isn't representable in MI,
there isn't much we can do.  Use %noreg (0) for those situations.
This matches the SelectionDAG behavior.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297200 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp b/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
index 3614333037c..8630ef842b4 100644
--- a/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
+++ b/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
@@ -137,8 +137,13 @@ MachineInstrBuilder MachineIRBuilder::buildConstDbgValue(const Constant &C,
       MIB.addCImm(CI);
     else
       MIB.addImm(CI->getZExtValue());
-  } else
+  } else if (auto *CFP = dyn_cast<ConstantFP>(&C)) {
+    assert(isa<ConstantFP>(C) && "Unexpected constant dbg value");
     MIB.addFPImm(&cast<ConstantFP>(C));
+  } else {
+    // Insert %noreg if we didn't find a usable constant and had to drop it.
+    MIB.addReg(0U);
+  }
 
   return MIB.addImm(Offset).addMetadata(Variable).addMetadata(Expr);
 }
diff --git a/test/CodeGen/AArch64/GlobalISel/debug-insts.ll b/test/CodeGen/AArch64/GlobalISel/debug-insts.ll
index ffd2c0c68b1..2c3def2e4a9 100644
--- a/test/CodeGen/AArch64/GlobalISel/debug-insts.ll
+++ b/test/CodeGen/AArch64/GlobalISel/debug-insts.ll
@@ -26,6 +26,8 @@ define void @debug_value(i32 %in) #0 !dbg !7 {
   call void @llvm.dbg.value(metadata i32 123, i64 0, metadata !11, metadata !12), !dbg !13
 ; CHECK: DBG_VALUE float 1.000000e+00, 0, !11, !12, debug-location !13
   call void @llvm.dbg.value(metadata float 1.000000e+00, i64 0, metadata !11, metadata !12), !dbg !13
+; CHECK: DBG_VALUE _, 0, !11, !12, debug-location !13
+  call void @llvm.dbg.value(metadata i32* null, i64 0, metadata !11, metadata !12), !dbg !13
   ret void
 }