GlobalISel: put debug info for static allocas in the MachineFunction.

The good reason to do this is that static allocas are pretty simple to handle
(especially at -O0) and avoiding tracking DBG_VALUEs throughout the pipeline
should give some kind of performance benefit.

The bad reason is that the debug pipeline is an unholy mess of implicit
contracts, where determining whether "DBG_VALUE %reg, imm" actually implies a
load or not involves the services of at least 3 soothsayers and the sacrifice
of at least one chicken.  And it still gets it wrong if the variable is at SP
directly.

llvm-svn: 297410

1 files changed, 8 insertions, 8 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 4d1ac680a45..b6ce59dc120 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -598,18 +598,18 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
       return true;
     }
 
-    unsigned Reg = getOrCreateVReg(*Address);
-    auto RegDef = MRI->def_instr_begin(Reg);
     assert(DI.getVariable()->isValidLocationForIntrinsic(
                MIRBuilder.getDebugLoc()) &&
            "Expected inlined-at fields to agree");
-
-    if (RegDef != MRI->def_instr_end() &&
-        RegDef->getOpcode() == TargetOpcode::G_FRAME_INDEX) {
-      MIRBuilder.buildFIDbgValue(RegDef->getOperand(1).getIndex(),
-                                 DI.getVariable(), DI.getExpression());
+    auto AI = dyn_cast<AllocaInst>(Address);
+    if (AI && AI->isStaticAlloca()) {
+      // Static allocas are tracked at the MF level, no need for DBG_VALUE
+      // instructions (in fact, they get ignored if they *do* exist).
+      MF->setVariableDbgInfo(DI.getVariable(), DI.getExpression(),
+                             getOrCreateFrameIndex(*AI), DI.getDebugLoc());
     } else
-      MIRBuilder.buildDirectDbgValue(Reg, DI.getVariable(), DI.getExpression());
+      MIRBuilder.buildDirectDbgValue(getOrCreateVReg(*Address),
+                                     DI.getVariable(), DI.getExpression());
     return true;
   }
   case Intrinsic::vaend: