- Split pseudo into VGSavePseudo & VGRestorePseudo.

kmclaughlin-arm · kmclaughlin-arm · commit 325b6b437479 · 2024-06-06T10:31:54.000Z
- Check for noexcept or nothrow when emitting Clang errors.
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3740,12 +3740,6 @@ def warn_gnu_inline_cplusplus_without_extern : Warning<
   "'gnu_inline' attribute without 'extern' in C++ treated as externally"
   " available, this changed in Clang 10">,
   InGroup<DiagGroup<"gnu-inline-cpp-without-extern">>;
-def warn_sme_streaming_mode_change_no_sve : Warning<
-  "function requires a streaming-mode change, unwinding is not possible without 'sve'">,
-  InGroup<AArch64SMEAttributes>;
-def warn_sme_locally_streaming_no_sve : Warning<
-  "unwinding is not possible for locally-streaming functions without 'sve'">,
-   InGroup<AArch64SMEAttributes>;
 def err_attribute_vecreturn_only_vector_member : Error<
   "the vecreturn attribute can only be used on a class or structure with one member, which must be a vector">;
 def err_attribute_vecreturn_only_pod_record : Error<
@@ -3782,6 +3776,12 @@ def err_conflicting_attributes_arm_state : Error<
   "conflicting attributes for state '%0'">;
 def err_sme_streaming_cannot_be_multiversioned : Error<
   "streaming function cannot be multi-versioned">;
+def err_sme_streaming_mode_change_no_sve : Error<
+  "function requires a streaming-mode change, unwinding is not possible without 'sve'. "
+  "Consider marking this function as 'noexcept' or '__attribute__((nothrow))'">;
+def err_sme_locally_streaming_no_sve : Error<
+  "unwinding is not possible for locally-streaming functions without 'sve'. "
+  "Consider marking this function as 'noexcept' or '__attribute__((nothrow))'">;
 def err_unknown_arm_state : Error<
   "unknown state '%0'">;
 def err_missing_arm_state : Error<
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
@@ -3920,17 +3920,22 @@ void Sema::checkCall(NamedDecl *FDecl, const FunctionProtoType *Proto,
           ExtInfo.AArch64SMEAttributes &
           FunctionType::SME_PStateSMCompatibleMask;
       SemaARM::ArmStreamingType CallerFnType = getArmStreamingFnType(CallerFD);
+      bool NoThrow =
+          !getLangOpts().Exceptions ||
+          (Proto && !isUnresolvedExceptionSpec(Proto->getExceptionSpecType()) &&
+           Proto->isNothrow()) ||
+          (FD && FD->hasAttr<NoThrowAttr>());
 
       // SME functions may require SVE to be available for unwinding, as the
       // value of VG needs to be preserved across streaming-mode changes.
-      if (!Context.getTargetInfo().hasFeature("sve")) {
+      if (!NoThrow && !Context.getTargetInfo().hasFeature("sve")) {
         if (CallerFD->hasAttr<ArmLocallyStreamingAttr>())
-          Diag(Loc, diag::warn_sme_locally_streaming_no_sve);
+          Diag(Loc, diag::err_sme_locally_streaming_no_sve);
 
         if ((CallerFnType == SemaARM::ArmStreaming ||
              CallerFnType == SemaARM::ArmStreamingCompatible) &&
             (!IsCalleeStreaming && !IsCalleeStreamingCompatible))
-          Diag(Loc, diag::warn_sme_streaming_mode_change_no_sve);
+          Diag(Loc, diag::err_sme_streaming_mode_change_no_sve);
       }
 
       // If the call requires a streaming-mode change and has scalable vector
diff --git a/clang/test/Sema/aarch64-sme-func-attrs-without-target-feature.cpp b/clang/test/Sema/aarch64-sme-func-attrs-without-target-feature.cpp
@@ -38,7 +38,7 @@ void non_streaming_def(void (*streaming_fn_ptr)(void) __arm_streaming,
 void streaming_compatible_def2(void (*streaming_fn_ptr)(void) __arm_streaming,
                                void (*streaming_compatible_fn_ptr)(void) __arm_streaming_compatible)
                                 __arm_streaming_compatible {
-  non_streaming_decl(); // expected-warning {{function requires a streaming-mode change, unwinding is not possible without 'sve'}}
+  non_streaming_decl();
   streaming_compatible_decl(); // OK
   streaming_compatible_fn_ptr(); // OK
   streaming_decl(); // expected-error {{call to a streaming function requires 'sme'}}
diff --git a/clang/test/Sema/aarch64-streaming-mode-changes-no-sve.c b/clang/test/Sema/aarch64-streaming-mode-changes-no-sve.c
diff --git a/clang/test/Sema/aarch64-streaming-mode-changes-no-sve.cpp b/clang/test/Sema/aarch64-streaming-mode-changes-no-sve.cpp
@@ -0,0 +1,89 @@
+// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -target-feature +sme \
+// RUN:  -target-feature -sve -fexceptions -DNO_THROW -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -target-feature +sme \
+// RUN:  -target-feature -sve -fexceptions -DNO_EXCEPT -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -target-feature +sme \
+// RUN:  -target-feature -sve -DNO_EXCEPT_FLAG -fsyntax-only -verify %s
+
+// REQUIRES: aarch64-registered-target
+
+#include "arm_sme.h"
+
+int non_streaming_decl(void);
+int streaming_decl(void) __arm_streaming;
+int streaming_compatible_decl(void) __arm_streaming_compatible;
+
+#ifdef NO_THROW
+#define NOTHROW_ATTR __attribute__((__nothrow__))
+#else
+#define NOTHROW_ATTR
+#endif
+
+#ifdef NO_EXCEPT
+#define NOEXCEPT_ATTR noexcept
+#else
+#define NOEXCEPT_ATTR
+#endif
+
+#ifdef NO_EXCEPT_FLAG
+  // expected-no-diagnostics
+#endif
+
+NOTHROW_ATTR int nothrow_non_streaming_decl(void) NOEXCEPT_ATTR;
+NOTHROW_ATTR int nothrow_streaming_decl(void) NOEXCEPT_ATTR;
+NOTHROW_ATTR int nothrow_streaming_compatible_decl(void) NOEXCEPT_ATTR;
+
+// Streaming-mode changes which would require spilling VG if unwinding is possible, unsupported without SVE
+
+int streaming_caller_no_sve(void) __arm_streaming {
+#ifndef NO_EXCEPT_FLAG
+  // expected-error@+2 {{function requires a streaming-mode change, unwinding is not possible without 'sve'. Consider marking this function as 'noexcept' or '__attribute__((nothrow))'}}
+#endif
+  return non_streaming_decl();
+}
+
+int sc_caller_non_streaming_callee(void) __arm_streaming_compatible {
+#ifndef NO_EXCEPT_FLAG
+  // expected-error@+2 {{function requires a streaming-mode change, unwinding is not possible without 'sve'. Consider marking this function as 'noexcept' or '__attribute__((nothrow))'}}
+#endif
+  return non_streaming_decl();
+}
+
+__arm_locally_streaming int locally_streaming_no_sve(void) {
+#ifndef NO_EXCEPT_FLAG
+  // expected-error@+2 {{unwinding is not possible for locally-streaming functions without 'sve'. Consider marking this function as 'noexcept' or '__attribute__((nothrow))'}}
+#endif
+  return streaming_decl();
+}
+
+// Nothrow / noexcept attribute on callee - warnings not expected
+
+int nothrow_streaming_caller_no_sve(void) __arm_streaming {
+  return nothrow_non_streaming_decl();
+}
+
+int nothrow_sc_caller_non_streaming_callee(void) __arm_streaming_compatible {
+  return nothrow_non_streaming_decl();
+}
+
+__arm_locally_streaming int nothrow_locally_streaming_no_sve(void) {
+  return nothrow_streaming_decl();
+}
+
+// No warnings expected, even if unwinding is possible
+
+int normal_caller_streaming_callee(void) {
+  return streaming_decl();
+}
+
+int normal_caller_streaming_compatible_callee(void) {
+  return streaming_compatible_decl();
+}
+
+int sc_caller_streaming_callee(void) __arm_streaming_compatible {
+  return streaming_decl();
+}
+
+int sc_caller_sc_callee(void) __arm_streaming_compatible {
+  return streaming_compatible_decl();
+}
diff --git a/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp b/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
@@ -1599,7 +1599,8 @@ bool AArch64ExpandPseudo::expandMI(MachineBasicBlock &MBB,
    case AArch64::COALESCER_BARRIER_FPR128:
      MI.eraseFromParent();
      return true;
-   case AArch64::VGUnwindInfoPseudo: {
+   case AArch64::VGSavePseudo:
+   case AArch64::VGRestorePseudo: {
      MachineFunction &MF = *MBB.getParent();
      SMEAttrs FuncAttrs(MF.getFunction());
      bool LocallyStreaming =
@@ -1617,7 +1618,8 @@ bool AArch64ExpandPseudo::expandMI(MachineBasicBlock &MBB,
      const TargetSubtargetInfo &STI = MF.getSubtarget();
      const TargetInstrInfo &TII = *STI.getInstrInfo();
      const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
-     if (MI.getOperand(0).getImm() == 1) {
+
+     if (Opcode == AArch64::VGSavePseudo) {
        // This pseudo has been inserted after a streaming-mode change
        // to save the streaming value of VG before a call.
        // Calculate and emit the CFI offset using VGFrameIdx.
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -2489,7 +2489,8 @@ const char *AArch64TargetLowering::getTargetNodeName(unsigned Opcode) const {
   case AArch64ISD::FIRST_NUMBER:
     break;
     MAKE_CASE(AArch64ISD::COALESCER_BARRIER)
-    MAKE_CASE(AArch64ISD::VG_UNWIND)
+    MAKE_CASE(AArch64ISD::VG_SAVE)
+    MAKE_CASE(AArch64ISD::VG_RESTORE)
     MAKE_CASE(AArch64ISD::SMSTART)
     MAKE_CASE(AArch64ISD::SMSTOP)
     MAKE_CASE(AArch64ISD::RESTORE_ZA)
@@ -8513,9 +8514,8 @@ AArch64TargetLowering::LowerCall(CallLoweringInfo &CLI,
   if (RequiresSMChange) {
 
     if (Subtarget->hasSVE()) {
-      Chain = DAG.getNode(
-          AArch64ISD::VG_UNWIND, DL, DAG.getVTList(MVT::Other, MVT::Glue),
-          {Chain, DAG.getTargetConstant(/*Save*/ 1, DL, MVT::i64)});
+      Chain = DAG.getNode(AArch64ISD::VG_SAVE, DL,
+                          DAG.getVTList(MVT::Other, MVT::Glue), Chain);
       InGlue = Chain.getValue(1);
     }
 
@@ -8700,9 +8700,9 @@ AArch64TargetLowering::LowerCall(CallLoweringInfo &CLI,
     InGlue = Result.getValue(1);
 
     if (Subtarget->hasSVE())
-      Result = DAG.getNode(
-          AArch64ISD::VG_UNWIND, DL, DAG.getVTList(MVT::Other, MVT::Glue),
-          {Result, DAG.getTargetConstant(/*Restore*/ 0, DL, MVT::i64), InGlue});
+      Result =
+          DAG.getNode(AArch64ISD::VG_RESTORE, DL,
+                      DAG.getVTList(MVT::Other, MVT::Glue), {Result, InGlue});
   }
 
   if (CallerAttrs.requiresEnablingZAAfterCall(CalleeAttrs))
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.h b/llvm/lib/Target/AArch64/AArch64ISelLowering.h
@@ -70,7 +70,8 @@ enum NodeType : unsigned {
 
   COALESCER_BARRIER,
 
-  VG_UNWIND,
+  VG_SAVE,
+  VG_RESTORE,
 
   SMSTART,
   SMSTOP,
diff --git a/llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td b/llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td
@@ -31,8 +31,11 @@ def AArch64_save_zt : SDNode<"AArch64ISD::SAVE_ZT", SDTypeProfile<0, 2,
 def AArch64CoalescerBarrier
     : SDNode<"AArch64ISD::COALESCER_BARRIER", SDTypeProfile<1, 1, []>, [SDNPOptInGlue, SDNPOutGlue]>;
 
-def AArch64VGUnwind : SDNode<"AArch64ISD::VG_UNWIND", SDTypeProfile<0, 1, []>,
-                             [SDNPHasChain, SDNPSideEffect, SDNPOptInGlue, SDNPOutGlue]>;
+def AArch64VGSave : SDNode<"AArch64ISD::VG_SAVE", SDTypeProfile<0, 0, []>,
+                           [SDNPHasChain, SDNPSideEffect, SDNPOptInGlue, SDNPOutGlue]>;
+
+def AArch64VGRestore : SDNode<"AArch64ISD::VG_RESTORE", SDTypeProfile<0, 0, []>,
+                              [SDNPHasChain, SDNPSideEffect, SDNPOptInGlue, SDNPOutGlue]>;
 
 //===----------------------------------------------------------------------===//
 // Instruction naming conventions.
@@ -227,11 +230,11 @@ def : Pat<(AArch64_smstop (i32 svcr_op:$pstate), (i64 /*AArch64SME::Always*/0)),
 // Pseudo to insert cfi_offset/cfi_restore instructions. Used to save or restore
 // the streaming value of VG around streaming-mode changes in locally-streaming
 // functions.
-def VGUnwindInfoPseudo :
-  Pseudo<(outs), (ins timm0_1:$save_restore), []>, Sched<[]>;
+def VGSavePseudo : Pseudo<(outs), (ins), []>, Sched<[]>;
+def : Pat<(AArch64VGSave), (VGSavePseudo)>;
 
-def : Pat<(AArch64VGUnwind (i64 timm0_1:$save_restore)),
-          (VGUnwindInfoPseudo timm0_1:$save_restore)>;
+def VGRestorePseudo : Pseudo<(outs), (ins), []>, Sched<[]>;
+def : Pat<(AArch64VGRestore), (VGRestorePseudo)>;
 
 //===----------------------------------------------------------------------===//
 // SME2 Instructions
