[CoroSplit][DebugInfo] Don't use entry_value for async args in 32-bit targets

Only X86_64 and ARM64 have a reserved register for async arguments, and so the
debugger is only able to handle those targets. For other architectures, we use a
non-entry-value expression and let the debugger do its best with that.

Differential Revision: https://reviews.llvm.org/D158638

Author: felipepiovezan

llvm/lib/Transforms/Coroutines/CoroFrame.cpp

@@ -1883,7 +1883,7 @@ static void insertSpills(const FrameDataInfo &FrameData, coro::Shape &Shape) {
           // This dbg.declare is for the main function entry point.  It
           // will be deleted in all coro-split functions.
           coro::salvageDebugInfo(ArgToAllocaMap, DDI, Shape.OptimizeFrame,
-                                 true /*IsEntryPoint*/);
+                                 false /*UseEntryValue*/);
         }
       }
 
@@ -2819,7 +2819,7 @@ static void collectFrameAlloca(AllocaInst *AI, coro::Shape &Shape,
 
 void coro::salvageDebugInfo(
     SmallDenseMap<Argument *, AllocaInst *, 4> &ArgToAllocaMap,
-    DbgVariableIntrinsic *DVI, bool OptimizeFrame, bool IsEntryPoint) {
+    DbgVariableIntrinsic *DVI, bool OptimizeFrame, bool UseEntryValue) {
   Function *F = DVI->getFunction();
   IRBuilder<> Builder(F->getContext());
   auto InsertPt = F->getEntryBlock().getFirstInsertionPt();
@@ -2874,7 +2874,7 @@ void coro::salvageDebugInfo(
   // For the EntryPoint funclet, don't use EntryValues. This funclet can be
   // inlined, which would remove the guarantee that this intrinsic targets an
   // Argument.
-  if (IsSwiftAsyncArg && !IsEntryPoint && !Expr->isEntryValue())
+  if (IsSwiftAsyncArg && UseEntryValue && !Expr->isEntryValue())
     Expr = DIExpression::prepend(Expr, DIExpression::EntryValue);
 
   // If the coroutine frame is an Argument, store it in an alloca to improve

llvm/lib/Transforms/Coroutines/CoroSplit.cpp

@@ -701,9 +701,13 @@ void CoroCloner::salvageDebugInfo() {
   SmallVector<DbgVariableIntrinsic *, 8> Worklist =
       collectDbgVariableIntrinsics(*NewF);
   SmallDenseMap<Argument *, AllocaInst *, 4> ArgToAllocaMap;
+
+  // Only 64-bit ABIs have a register we can refer to with the entry value.
+  bool UseEntryValue =
+      llvm::Triple(OrigF.getParent()->getTargetTriple()).isArch64Bit();
   for (DbgVariableIntrinsic *DVI : Worklist)
     coro::salvageDebugInfo(ArgToAllocaMap, DVI, Shape.OptimizeFrame,
-                           false /*IsEntryPoint*/);
+                           UseEntryValue);
 
   // Remove all salvaged dbg.declare intrinsics that became
   // either unreachable or stale due to the CoroSplit transformation.
@@ -1997,7 +2001,7 @@ splitCoroutine(Function &F, SmallVectorImpl<Function *> &Clones,
   SmallDenseMap<Argument *, AllocaInst *, 4> ArgToAllocaMap;
   for (auto *DDI : collectDbgVariableIntrinsics(F))
     coro::salvageDebugInfo(ArgToAllocaMap, DDI, Shape.OptimizeFrame,
-                           true /*IsEntryPoint*/);
+                           false /*UseEntryValue*/);
 
   return Shape;
 }

llvm/test/Transforms/Coroutines/swift-async-dbg.ll

@@ -1,6 +1,10 @@
-; RUN: opt %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s
+; RUN: opt -mtriple='arm64-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s
+; RUN: opt -mtriple='x86_64' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s
+; RUN: opt -mtriple='i386-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s --check-prefix=NOENTRY
+; RUN: opt -mtriple='armv7-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s --check-prefix=NOENTRY
+; NOENTRY-NOT: OP_llvm_entry_value
+
 target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
-target triple = "arm64-apple-macosx13.0.0"
 
 ; This coroutine has one split point and two variables defined by:
 ;   %var_with_dbg_value,   which has multiple dbg.value intrinsics associated with