Disable tail-call optimization for X86 interrupt handlers

[aaboud]

Summary

Resolved Bug 26414.
https://llvm.org/bugs/show_bug.cgi?id=26414

Since interrupt handler must be returned with iretq, tail call can't be used.

[ABataev]

LG

lib/CodeGen/CGCall.cpp

void CodeGenModule::ConstructAttributeList(
 
   // If we have information about the function prototype, we can learn
   // attributes form there.
   AddAttributesFromFunctionProtoType(getContext(), FuncAttrs,
                                      CalleeInfo.getCalleeFunctionProtoType());
 
   const Decl *TargetDecl = CalleeInfo.getCalleeDecl();
 
+  bool HasAnyX86InterruptAttr = false;
   // FIXME: handle sseregparm someday...
   if (TargetDecl) {
     if (TargetDecl->hasAttr<ReturnsTwiceAttr>())
       FuncAttrs.addAttribute(llvm::Attribute::ReturnsTwice);
     if (TargetDecl->hasAttr<NoThrowAttr>())
       FuncAttrs.addAttribute(llvm::Attribute::NoUnwind);
     if (TargetDecl->hasAttr<NoReturnAttr>())
       FuncAttrs.addAttribute(llvm::Attribute::NoReturn);
if (TargetDecl->hasAttr<ConstAttr>()) {
       FuncAttrs.addAttribute(llvm::Attribute::ArgMemOnly);
       FuncAttrs.addAttribute(llvm::Attribute::NoUnwind);
     }
     if (TargetDecl->hasAttr<RestrictAttr>())
       RetAttrs.addAttribute(llvm::Attribute::NoAlias);
     if (TargetDecl->hasAttr<ReturnsNonNullAttr>())
       RetAttrs.addAttribute(llvm::Attribute::NonNull);
 
+    HasAnyX86InterruptAttr = TargetDecl->hasAttr<AnyX86InterruptAttr>();
     HasOptnone = TargetDecl->hasAttr<OptimizeNoneAttr>();
   }
 
   // OptimizeNoneAttr takes precedence over -Os or -Oz. No warning needed.
   if (!HasOptnone) {
     if (CodeGenOpts.OptimizeSize)
       FuncAttrs.addAttribute(llvm::Attribute::OptimizeForSize);
     if (CodeGenOpts.OptimizeSize == 2)
if (!CodeGenOpts.DisableFPElim) {
       FuncAttrs.addAttribute("no-frame-pointer-elim", "false");
       FuncAttrs.addAttribute("no-frame-pointer-elim-non-leaf");
     } else {
       FuncAttrs.addAttribute("no-frame-pointer-elim", "true");
       FuncAttrs.addAttribute("no-frame-pointer-elim-non-leaf");
     }
 
     bool DisableTailCalls =
-        CodeGenOpts.DisableTailCalls ||
+        CodeGenOpts.DisableTailCalls || HasAnyX86InterruptAttr ||
         (TargetDecl && TargetDecl->hasAttr<DisableTailCallsAttr>());
-    FuncAttrs.addAttribute("disable-tail-calls",
-                           llvm::toStringRef(DisableTailCalls));
+    FuncAttrs.addAttribute(
+        "disable-tail-calls",
 
     FuncAttrs.addAttribute("less-precise-fpmad",
                            llvm::toStringRef(CodeGenOpts.LessPreciseFPMAD));
     FuncAttrs.addAttribute("no-infs-fp-math",
                            llvm::toStringRef(CodeGenOpts.NoInfsFPMath));
     FuncAttrs.addAttribute("no-nans-fp-math",
                            llvm::toStringRef(CodeGenOpts.NoNaNsFPMath));
     FuncAttrs.addAttribute("unsafe-fp-math",

test/CodeGen/attr-x86-interrupt.c

 typedef __UINT32_TYPE__ uword;
 #endif
 
 __attribute__((interrupt)) void foo7(int *a, uword b) {}
 __attribute__((interrupt)) void foo8(int *a) {}
 // X86_64_LINUX: @llvm.used = appending global [2 x i8*] [i8* bitcast (void (i32*, i64)* @foo7 to i8*), i8* bitcast (void (i32*)* @foo8 to i8*)], section "llvm.metadata"
 // X86_64_LINUX: define x86_intrcc void @foo7(i32* %{{.+}}, i64 %{{.+}})
 // X86_64_LINUX: define x86_intrcc void @foo8(i32* %{{.+}})
+// X86_64_LINUX: "disable-tail-calls"="true"
+// X86_64_LINUX-NOT: "disable-tail-calls"="false"
 // X86_LINUX: @llvm.used = appending global [2 x i8*] [i8* bitcast (void (i32*, i32)* @foo7 to i8*), i8* bitcast (void (i32*)* @foo8 to i8*)], section "llvm.metadata"
 // X86_LINUX: define x86_intrcc void @foo7(i32* %{{.+}}, i32 %{{.+}})
 // X86_LINUX: define x86_intrcc void @foo8(i32* %{{.+}})
+// X86_LINUX: "disable-tail-calls"="true"
+// X86_LINUX-NOT: "disable-tail-calls"="false"
 // X86_64_WIN: @llvm.used = appending global [2 x i8*] [i8* bitcast (void (i32*, i64)* @foo7 to i8*), i8* bitcast (void (i32*)* @foo8 to i8*)], section "llvm.metadata"
 // X86_64_WIN: define x86_intrcc void @foo7(i32* %{{.+}}, i64 %{{.+}})
 // X86_64_WIN: define x86_intrcc void @foo8(i32* %{{.+}})
+// X86_64_Win: "disable-tail-calls"="true"
+// X86_64_Win-NOT: "disable-tail-calls"="false"
 // X86_WIN: @llvm.used = appending global [2 x i8*] [i8* bitcast (void (i32*, i32)* @foo7 to i8*), i8* bitcast (void (i32*)* @foo8 to i8*)], section "llvm.metadata"
 // X86_WIN: define x86_intrcc void @foo7(i32* %{{.+}}, i32 %{{.+}})
 // X86_WIN: define x86_intrcc void @foo8(i32* %{{.+}})
+// X86_Win: "disable-tail-calls"="true"
+// X86_Win-NOT: "disable-tail-calls"="false"