[PATCH] D96053: [clang] add new unwind inline asm clobber which lowers to throwable inline assembly

[Paul via Phabricator via cfe-commits]

cynecx created this revision.
cynecx requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D96053

Files:
  clang/lib/Basic/TargetInfo.cpp
  clang/lib/CodeGen/CGStmt.cpp
  clang/lib/Sema/SemaStmtAsm.cpp


Index: clang/lib/Sema/SemaStmtAsm.cpp
===================================================================
--- clang/lib/Sema/SemaStmtAsm.cpp
+++ clang/lib/Sema/SemaStmtAsm.cpp
@@ -228,7 +228,7 @@
     StringRef Clobber = Clobbers[i]->getString();
     // We only check registers, therefore we don't check cc and memory
     // clobbers
-    if (Clobber == "cc" || Clobber == "memory")
+    if (Clobber == "cc" || Clobber == "memory" || Clobber == "unwind")
       continue;
     Clobber = Target.getNormalizedGCCRegisterName(Clobber, true);
     // Go over the output's registers we collected
Index: clang/lib/CodeGen/CGStmt.cpp
===================================================================
--- clang/lib/CodeGen/CGStmt.cpp
+++ clang/lib/CodeGen/CGStmt.cpp
@@ -2115,13 +2115,15 @@
 }
 
 static void UpdateAsmCallInst(llvm::CallBase &Result, bool HasSideEffect,
-                              bool ReadOnly, bool ReadNone, bool NoMerge,
-                              const AsmStmt &S,
+                              bool HasUnwindClobber, bool ReadOnly,
+                              bool ReadNone, bool NoMerge, const AsmStmt &S,
                               const std::vector<llvm::Type *> &ResultRegTypes,
                               CodeGenFunction &CGF,
                               std::vector<llvm::Value *> &RegResults) {
-  Result.addAttribute(llvm::AttributeList::FunctionIndex,
-                      llvm::Attribute::NoUnwind);
+  if (!HasUnwindClobber)
+    Result.addAttribute(llvm::AttributeList::FunctionIndex,
+                        llvm::Attribute::NoUnwind);
+
   if (NoMerge)
     Result.addAttribute(llvm::AttributeList::FunctionIndex,
                         llvm::Attribute::NoMerge);
@@ -2468,13 +2470,18 @@
   }
   Constraints += InOutConstraints;
 
+  bool HasUnwindClobber = false;
+
   // Clobbers
   for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) {
     StringRef Clobber = S.getClobber(i);
 
     if (Clobber == "memory")
       ReadOnly = ReadNone = false;
-    else if (Clobber != "cc") {
+    else if (Clobber == "unwind") {
+      HasUnwindClobber = true;
+      continue;
+    } else if (Clobber != "cc") {
       Clobber = getTarget().getNormalizedGCCRegisterName(Clobber);
       if (CGM.getCodeGenOpts().StackClashProtector &&
           getTarget().isSPRegName(Clobber)) {
@@ -2508,6 +2515,9 @@
     Constraints += '}';
   }
 
+  assert(!(HasUnwindClobber && IsGCCAsmGoto) &&
+         "unwind clobber can't be used with asm goto");
+
   // Add machine specific clobbers
   std::string MachineClobbers = getTarget().getClobbers();
   if (!MachineClobbers.empty()) {
@@ -2530,23 +2540,28 @@
   bool HasSideEffect = S.isVolatile() || S.getNumOutputs() == 0;
   llvm::InlineAsm::AsmDialect AsmDialect = isa<MSAsmStmt>(&S) ?
     llvm::InlineAsm::AD_Intel : llvm::InlineAsm::AD_ATT;
-  llvm::InlineAsm *IA =
-    llvm::InlineAsm::get(FTy, AsmString, Constraints, HasSideEffect,
-                         /* IsAlignStack */ false, AsmDialect);
+  llvm::InlineAsm *IA = llvm::InlineAsm::get(
+      FTy, AsmString, Constraints, HasSideEffect,
+      /* IsAlignStack */ false, AsmDialect, HasUnwindClobber);
   std::vector<llvm::Value*> RegResults;
   if (IsGCCAsmGoto) {
     llvm::CallBrInst *Result =
         Builder.CreateCallBr(IA, Fallthrough, Transfer, Args);
     EmitBlock(Fallthrough);
-    UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, ReadOnly,
-                      ReadNone, InNoMergeAttributedStmt, S, ResultRegTypes,
-                      *this, RegResults);
+    UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, false,
+                      ReadOnly, ReadNone, InNoMergeAttributedStmt, S,
+                      ResultRegTypes, *this, RegResults);
+  } else if (HasUnwindClobber) {
+    llvm::CallBase *Result = EmitCallOrInvoke(IA, Args, "");
+    UpdateAsmCallInst(*Result, HasSideEffect, true, ReadOnly, ReadNone,
+                      InNoMergeAttributedStmt, S, ResultRegTypes, *this,
+                      RegResults);
   } else {
     llvm::CallInst *Result =
         Builder.CreateCall(IA, Args, getBundlesForFunclet(IA));
-    UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, ReadOnly,
-                      ReadNone, InNoMergeAttributedStmt, S, ResultRegTypes,
-                      *this, RegResults);
+    UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, false,
+                      ReadOnly, ReadNone, InNoMergeAttributedStmt, S,
+                      ResultRegTypes, *this, RegResults);
   }
 
   assert(RegResults.size() == ResultRegTypes.size());
Index: clang/lib/Basic/TargetInfo.cpp
===================================================================
--- clang/lib/Basic/TargetInfo.cpp
+++ clang/lib/Basic/TargetInfo.cpp
@@ -475,8 +475,8 @@
 /// a valid clobber in an inline asm statement. This is used by
 /// Sema.
 bool TargetInfo::isValidClobber(StringRef Name) const {
-  return (isValidGCCRegisterName(Name) ||
-          Name == "memory" || Name == "cc");
+  return (isValidGCCRegisterName(Name) || Name == "memory" || Name == "cc" ||
+          Name == "unwind");
 }
 
 /// isValidGCCRegisterName - Returns whether the passed in string

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