[mips] Interrupt attribute support.

Summary: This patch adds support for the interrupt attribute for mips32r2+.

Patch by Simon Dardis.

Reviewers: dsanders, aaron.ballman

Subscribers: aaron.ballman, cfe-commits

Differential Revision: http://reviews.llvm.org/D10802

llvm-svn: 254205

clang/include/clang/Basic/Attr.td

@@ -426,8 +426,8 @@ def Annotate : InheritableParamAttr {
 }
 
 def ARMInterrupt : InheritableAttr, TargetSpecificAttr<TargetARM> {
-  // NOTE: If you add any additional spellings, MSP430Interrupt's spellings
-  // must match.
+  // NOTE: If you add any additional spellings, MSP430Interrupt's and
+  // MipsInterrupt's spellings must match.
   let Spellings = [GNU<"interrupt">];
   let Args = [EnumArgument<"Interrupt", "InterruptType",
                            ["IRQ", "FIQ", "SWI", "ABORT", "UNDEF", ""],
@@ -845,8 +845,8 @@ def MSABI : InheritableAttr {
 }
 
 def MSP430Interrupt : InheritableAttr, TargetSpecificAttr<TargetMSP430> {
-  // NOTE: If you add any additional spellings, ARMInterrupt's spellings must
-  // match.
+  // NOTE: If you add any additional spellings, ARMInterrupt's and
+  // MipsInterrupt's spellings must match.
   let Spellings = [GNU<"interrupt">];
   let Args = [UnsignedArgument<"Number">];
   let ParseKind = "Interrupt";
@@ -860,6 +860,22 @@ def Mips16 : InheritableAttr, TargetSpecificAttr<TargetMips> {
   let Documentation = [Undocumented];
 }
 
+def MipsInterrupt : InheritableAttr, TargetSpecificAttr<TargetMips> {
+  // NOTE: If you add any additional spellings, ARMInterrupt's and
+  // MSP430Interrupt's spellings must match.
+  let Spellings = [GNU<"interrupt">];
+  let Subjects = SubjectList<[Function]>;
+  let Args = [EnumArgument<"Interrupt", "InterruptType",
+                           ["vector=sw0", "vector=sw1", "vector=hw0",
+                            "vector=hw1", "vector=hw2", "vector=hw3",
+                            "vector=hw4", "vector=hw5", "eic", ""],
+                           ["sw0", "sw1", "hw0", "hw1", "hw2", "hw3",
+                            "hw4", "hw5", "eic", "eic"]
+                           >];
+  let ParseKind = "Interrupt";
+  let Documentation = [MipsInterruptDocs];
+}
+
 def Mode : Attr {
   let Spellings = [GCC<"mode">];
   let Args = [IdentifierArgument<"Mode">];

clang/include/clang/Basic/AttrDocs.td

@@ -714,6 +714,46 @@ The semantics are as follows:
   }];
 }
 
+def MipsInterruptDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+Clang supports the GNU style ``__attribute__((interrupt("ARGUMENT")))`` attribute on
+MIPS targets. This attribute may be attached to a function definition and instructs
+the backend to generate appropriate function entry/exit code so that it can be used
+directly as an interrupt service routine.
+
+By default, the compiler will produce a function prologue and epilogue suitable for
+an interrupt service routine that handles an External Interrupt Controller (eic)
+generated interrupt. This behaviour can be explicitly requested with the "eic"
+argument.
+
+Otherwise, for use with vectored interrupt mode, the argument passed should be
+of the form "vector=LEVEL" where LEVEL is one of the following values:
+"sw0", "sw1", "hw0", "hw1", "hw2", "hw3", "hw4", "hw5". The compiler will
+then set the interrupt mask to the corresponding level which will mask all
+interrupts up to and including the argument.
+
+The semantics are as follows:
+
+- The prologue is modified so that the Exception Program Counter (EPC) and
+  Status coprocessor registers are saved to the stack. The interrupt mask is
+  set so that the function can only be interrupted by a higher priority
+  interrupt. The epilogue will restore the previous values of EPC and Status.
+
+- The prologue and epilogue are modified to save and restore all non-kernel
+  registers as necessary.
+
+- The FPU is disabled in the prologue, as the floating pointer registers are not
+  spilled to the stack.
+
+- The function return sequence is changed to use an exception return instruction.
+
+- The parameter sets the interrupt mask for the function corresponding to the
+  interrupt level specified. If no mask is specified the interrupt mask
+  defaults to "eic".
+  }];
+}
+
 def TargetDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -255,6 +255,10 @@ def err_bad_variable_name : Error<
 def err_bad_parameter_name : Error<
   "%0 cannot be the name of a parameter">;
 def err_parameter_name_omitted : Error<"parameter name omitted">;
+def warn_mips_interrupt_attribute : Warning<
+   "MIPS 'interrupt' attribute only applies to functions that have "
+   "%select{no parameters|a 'void' return type}0">,
+   InGroup<IgnoredAttributes>;
 def warn_unused_parameter : Warning<"unused parameter %0">,
   InGroup<UnusedParameter>, DefaultIgnore;
 def warn_unused_variable : Warning<"unused variable %0">,

clang/lib/CodeGen/TargetInfo.cpp

@@ -5893,6 +5893,27 @@ public:
     else if (FD->hasAttr<NoMips16Attr>()) {
       Fn->addFnAttr("nomips16");
     }
+
+    const MipsInterruptAttr *Attr = FD->getAttr<MipsInterruptAttr>();
+    if (!Attr)
+      return;
+
+    const char *Kind;
+    switch (Attr->getInterrupt()) {
+    default: llvm_unreachable("Unknown Mips interrupt attribute type!");
+    case MipsInterruptAttr::eic:     Kind = "eic"; break;
+    case MipsInterruptAttr::sw0:     Kind = "sw0"; break;
+    case MipsInterruptAttr::sw1:     Kind = "sw1"; break;
+    case MipsInterruptAttr::hw0:     Kind = "hw0"; break;
+    case MipsInterruptAttr::hw1:     Kind = "hw1"; break;
+    case MipsInterruptAttr::hw2:     Kind = "hw2"; break;
+    case MipsInterruptAttr::hw3:     Kind = "hw3"; break;
+    case MipsInterruptAttr::hw4:     Kind = "hw4"; break;
+    case MipsInterruptAttr::hw5:     Kind = "hw5"; break;
+    }
+
+    Fn->addFnAttr("interrupt", Kind);
+
   }
 
   bool initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,

clang/lib/Sema/SemaDeclAttr.cpp

@@ -4450,14 +4450,86 @@ static void handleMSP430InterruptAttr(Sema &S, Decl *D,
   D->addAttr(UsedAttr::CreateImplicit(S.Context));
 }
 
+static void handleMipsInterruptAttr(Sema &S, Decl *D,
+                                    const AttributeList &Attr) {
+  // Only one optional argument permitted.
+  if (Attr.getNumArgs() > 1) {
+    S.Diag(Attr.getLoc(), diag::err_attribute_too_many_arguments)
+        << Attr.getName() << 1;
+    return;
+  }
+
+  StringRef Str;
+  SourceLocation ArgLoc;
+
+  if (Attr.getNumArgs() == 0)
+    Str = "";
+  else if (!S.checkStringLiteralArgumentAttr(Attr, 0, Str, &ArgLoc))
+    return;
+
+  // Semantic checks for a function with the 'interrupt' attribute for MIPS:
+  // a) Must be a function.
+  // b) Must have no parameters.
+  // c) Must have the 'void' return type.
+  // d) Cannot have the 'mips16' attribute, as that instruction set
+  //    lacks the 'eret' instruction.
+  // e) The attribute itself must either have no argument or one of the
+  //    valid interrupt types, see [MipsInterruptDocs].
+
+  if (!isFunctionOrMethod(D)) {
+    S.Diag(D->getLocation(), diag::warn_attribute_wrong_decl_type)
+        << "'interrupt'" << ExpectedFunctionOrMethod;
+    return;
+  }
+
+  if (hasFunctionProto(D) && getFunctionOrMethodNumParams(D) != 0) {
+    S.Diag(D->getLocation(), diag::warn_mips_interrupt_attribute)
+        << 0;
+    return;
+  }
+
+  if (!getFunctionOrMethodResultType(D)->isVoidType()) {
+    S.Diag(D->getLocation(), diag::warn_mips_interrupt_attribute)
+        << 1;
+    return;
+  }
+
+  if (checkAttrMutualExclusion<Mips16Attr>(S, D, Attr.getRange(),
+                                           Attr.getName()))
+    return;
+
+  MipsInterruptAttr::InterruptType Kind;
+  if (!MipsInterruptAttr::ConvertStrToInterruptType(Str, Kind)) {
+    S.Diag(Attr.getLoc(), diag::warn_attribute_type_not_supported)
+        << Attr.getName() << "'" + std::string(Str) + "'";
+    return;
+  }
+
+  D->addAttr(::new (S.Context) MipsInterruptAttr(
+      Attr.getLoc(), S.Context, Kind, Attr.getAttributeSpellingListIndex()));
+}
+
 static void handleInterruptAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   // Dispatch the interrupt attribute based on the current target.
   if (S.Context.getTargetInfo().getTriple().getArch() == llvm::Triple::msp430)
     handleMSP430InterruptAttr(S, D, Attr);
+  else if (S.Context.getTargetInfo().getTriple().getArch() ==
+               llvm::Triple::mipsel ||
+           S.Context.getTargetInfo().getTriple().getArch() ==
+               llvm::Triple::mips)
+    handleMipsInterruptAttr(S, D, Attr);
   else
     handleARMInterruptAttr(S, D, Attr);
 }
 
+static void handleMips16Attribute(Sema &S, Decl *D, const AttributeList &Attr) {
+  if (checkAttrMutualExclusion<MipsInterruptAttr>(S, D, Attr.getRange(),
+                                                  Attr.getName()))
+    return;
+
+  handleSimpleAttribute<Mips16Attr>(S, D, Attr);
+}
+
 static void handleAMDGPUNumVGPRAttr(Sema &S, Decl *D,
                                     const AttributeList &Attr) {
   uint32_t NumRegs;
@@ -4847,7 +4919,7 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
     handleDLLAttr(S, D, Attr);
     break;
   case AttributeList::AT_Mips16:
-    handleSimpleAttribute<Mips16Attr>(S, D, Attr);
+    handleMips16Attribute(S, D, Attr);
     break;
   case AttributeList::AT_NoMips16:
     handleSimpleAttribute<NoMips16Attr>(S, D, Attr);

clang/test/CodeGen/mips-interrupt-attr.c

@@ -0,0 +1,64 @@
+// RUN: %clang_cc1 -triple mipsel-unknown-linux -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK
+
+void __attribute__ ((interrupt("vector=sw0")))
+isr_sw0 (void)
+{
+  // CHECK: define void @isr_sw0() [[SW0:#[0-9]+]]
+}
+
+void __attribute__ ((interrupt("vector=sw1")))
+isr_sw1 (void)
+{
+  // CHECK: define void @isr_sw1() [[SW1:#[0-9]+]]
+}
+
+void __attribute__ ((interrupt("vector=hw0")))
+isr_hw0 (void)
+{
+  // CHECK: define void @isr_hw0() [[HW0:#[0-9]+]]
+}
+
+void __attribute__ ((interrupt("vector=hw1")))
+isr_hw1 (void)
+{
+  // CHECK: define void @isr_hw1() [[HW1:#[0-9]+]]
+}
+
+void __attribute__ ((interrupt("vector=hw2")))
+isr_hw2 (void)
+{
+  // CHECK: define void @isr_hw2() [[HW2:#[0-9]+]]
+}
+
+void __attribute__ ((interrupt("vector=hw3")))
+isr_hw3 (void)
+{
+  // CHECK: define void @isr_hw3() [[HW3:#[0-9]+]]
+}
+
+void __attribute__ ((interrupt("vector=hw4")))
+isr_hw4 (void)
+{
+  // CHECK: define void @isr_hw4() [[HW4:#[0-9]+]]
+}
+
+void __attribute__ ((interrupt("vector=hw5")))
+isr_hw5 (void)
+{
+  // CHECK: define void @isr_hw5() [[HW5:#[0-9]+]]
+}
+
+void __attribute__ ((interrupt))
+isr_eic (void)
+{
+  // CHECK: define void @isr_eic() [[EIC:#[0-9]+]]
+}
+// CHECK: attributes [[SW0]] = { {{.*}} "interrupt"="sw0" {{.*}} }
+// CHECK: attributes [[SW1]] = { {{.*}} "interrupt"="sw1" {{.*}} }
+// CHECK: attributes [[HW0]] = { {{.*}} "interrupt"="hw0" {{.*}} }
+// CHECK: attributes [[HW1]] = { {{.*}} "interrupt"="hw1" {{.*}} }
+// CHECK: attributes [[HW2]] = { {{.*}} "interrupt"="hw2" {{.*}} }
+// CHECK: attributes [[HW3]] = { {{.*}} "interrupt"="hw3" {{.*}} }
+// CHECK: attributes [[HW4]] = { {{.*}} "interrupt"="hw4" {{.*}} }
+// CHECK: attributes [[HW5]] = { {{.*}} "interrupt"="hw5" {{.*}} }
+// CHECK: attributes [[EIC]] = { {{.*}} "interrupt"="eic" {{.*}} }

clang/test/Sema/mips-interrupt-attr.c

@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 %s -triple mips-img-elf -verify -fsyntax-only
+struct a { int b; };
+
+struct a test __attribute__((interrupt)); // expected-warning {{'interrupt' attribute only applies to functions and methods}}
+
+__attribute__((interrupt("EIC"))) void foo1() {} // expected-warning {{'interrupt' attribute argument not supported: 'EIC'}}
+
+__attribute__((interrupt("eic", 1))) void foo2() {} // expected-error {{'interrupt' attribute takes no more than 1 argument}}
+
+__attribute__((interrupt("eic"))) void foo3() {}
+__attribute__((interrupt("vector=sw0"))) void foo4() {}
+__attribute__((interrupt("vector=hw0"))) void foo5() {}
+__attribute__((interrupt("vector=hw1"))) void foo6() {}
+__attribute__((interrupt("vector=hw2"))) void foo7() {}
+__attribute__((interrupt("vector=hw3"))) void foo8() {}
+__attribute__((interrupt("vector=hw4"))) void foo9() {}
+__attribute__((interrupt("vector=hw5"))) void fooa() {}
+__attribute__((interrupt(""))) void food() {}
+
+__attribute__((interrupt)) int foob() {return 0;} // expected-warning {{MIPS 'interrupt' attribute only applies to functions that have a 'void' return type}}
+__attribute__((interrupt())) void fooc(int a) {} // expected-warning {{MIPS 'interrupt' attribute only applies to functions that have no parameters}}
+__attribute__((interrupt,mips16)) void fooe() {} // expected-error {{'interrupt' and 'mips16' attributes are not compatible}} \
+                                                 // expected-note {{conflicting attribute is here}}
+__attribute__((mips16,interrupt)) void foof() {} // expected-error {{'mips16' and 'interrupt' attributes are not compatible}} \
+                                                 // expected-note {{conflicting attribute is here}}
+__attribute__((interrupt)) __attribute__ ((mips16)) void foo10() {} // expected-error {{'interrupt' and 'mips16' attributes are not compatible}} \
+                                                                    // expected-note {{conflicting attribute is here}}
+__attribute__((mips16)) __attribute ((interrupt)) void foo11() {} // expected-error {{'mips16' and 'interrupt' attributes are not compatible}} \
+                                                                  // expected-note {{conflicting attribute is here}}