sdesmalen created this revision.
sdesmalen added reviewers: rsandifo-arm, aaron.ballman.
Herald added subscribers: ctetreau, hiraditya, kristof.beyls.
Herald added a project: All.
sdesmalen requested review of this revision.
Herald added projects: clang, LLVM.
Herald added subscribers: llvm-commits, cfe-commits.
This patch adds error diagnostics to Clang when code uses the AArch64 SME
attributes without specifying 'sme' as available target attribute.
- Function definitions marked as '__arm_streaming', '__arm_locally_streaming',
'__arm_shared_za' or '__arm_new_za' will by definition use or require SME
instructions.
- Calls from non-streaming functions to streaming-functions require the
compiler to enable/disable streaming-SVE mode around the call-site.
In some cases we can accept the SME attributes without having 'sme' enabled:
- Function declaration can have the SME attributes.
- Definitions can be __arm_streaming_compatible since the generated code should
execute on processing elements without SME.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D157269
Files:
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaChecking.cpp
clang/lib/Sema/SemaDecl.cpp
clang/test/Sema/aarch64-sme-func-attrs-without-target-feature.cpp
llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td
llvm/test/CodeGen/AArch64/sme-call-streaming-compatible-to-normal-fn-wihout-sme-attr.ll
Index: llvm/test/CodeGen/AArch64/sme-call-streaming-compatible-to-normal-fn-wihout-sme-attr.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/sme-call-streaming-compatible-to-normal-fn-wihout-sme-attr.ll
@@ -0,0 +1,41 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+; RUN: llc < %s | FileCheck %s
+
+; This that the following code can be compiled without +sme, because if the
+; call is not entered in streaming-SVE mode at runtime, the codepath leading
+; to the smstop/smstart pair will not be executed either.
+
+target triple = "aarch64"
+
+define void @streaming_compatible() #0 {
+; CHECK-LABEL: streaming_compatible:
+; CHECK: // %bb.0:
+; CHECK-NEXT: stp d15, d14, [sp, #-80]! // 16-byte Folded Spill
+; CHECK-NEXT: stp d13, d12, [sp, #16] // 16-byte Folded Spill
+; CHECK-NEXT: stp d11, d10, [sp, #32] // 16-byte Folded Spill
+; CHECK-NEXT: stp d9, d8, [sp, #48] // 16-byte Folded Spill
+; CHECK-NEXT: stp x30, x19, [sp, #64] // 16-byte Folded Spill
+; CHECK-NEXT: bl __arm_sme_state
+; CHECK-NEXT: and x19, x0, #0x1
+; CHECK-NEXT: tbz x19, #0, .LBB0_2
+; CHECK-NEXT: // %bb.1:
+; CHECK-NEXT: msr SVCRSM, #0
+; CHECK-NEXT: .LBB0_2:
+; CHECK-NEXT: bl non_streaming
+; CHECK-NEXT: tbz x19, #0, .LBB0_4
+; CHECK-NEXT: // %bb.3:
+; CHECK-NEXT: msr SVCRSM, #1
+; CHECK-NEXT: .LBB0_4:
+; CHECK-NEXT: ldp x30, x19, [sp, #64] // 16-byte Folded Reload
+; CHECK-NEXT: ldp d9, d8, [sp, #48] // 16-byte Folded Reload
+; CHECK-NEXT: ldp d11, d10, [sp, #32] // 16-byte Folded Reload
+; CHECK-NEXT: ldp d13, d12, [sp, #16] // 16-byte Folded Reload
+; CHECK-NEXT: ldp d15, d14, [sp], #80 // 16-byte Folded Reload
+; CHECK-NEXT: ret
+ call void @non_streaming()
+ ret void
+}
+
+declare void @non_streaming()
+
+attributes #0 = { nounwind "aarch64_pstate_sm_compatible" "target-features"="+sve" }
Index: llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td
===================================================================
--- llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td
+++ llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td
@@ -154,6 +154,13 @@
let Inst{11-9} = pstatefield;
let Inst{8} = imm;
let Inst{7-5} = 0b011; // op2
+
+ // Rather than only allowing this instruction with '+sme', we also
+ // allow it with '+sve', such that we can still emit the instruction
+ // for streaming-compatible functions which call non-streaming functions.
+ // The SME smstart/smstop will only be executed at runtime if streaming-mode
+ // is enabled, which also means SME must be enabled.
+ let Predicates = [HasSVEorSME];
}
def : InstAlias<"smstart", (MSRpstatesvcrImm1 0b011, 0b1)>;
@@ -226,11 +233,13 @@
def : Pat<(AArch64_smstop (i32 svcr_op:$pstate), (i64 0), (i64 1)), // after call
(MSRpstatesvcrImm1 svcr_op:$pstate, 0b0)>;
+let Predicates = [HasSVEorSME] in {
// The generic case which gets expanded to a pseudo node.
def : Pat<(AArch64_smstart (i32 svcr_op:$pstate), (i64 GPR64:$rtpstate), (i64 timm0_1:$expected_pstate)),
(MSRpstatePseudo svcr_op:$pstate, 0b1, GPR64:$rtpstate, timm0_1:$expected_pstate)>;
def : Pat<(AArch64_smstop (i32 svcr_op:$pstate), (i64 GPR64:$rtpstate), (i64 timm0_1:$expected_pstate)),
(MSRpstatePseudo svcr_op:$pstate, 0b0, GPR64:$rtpstate, timm0_1:$expected_pstate)>;
+}
// Read and write TPIDR2_EL0
def : Pat<(int_aarch64_sme_set_tpidr2 i64:$val),
Index: clang/test/Sema/aarch64-sme-func-attrs-without-target-feature.cpp
===================================================================
--- /dev/null
+++ clang/test/Sema/aarch64-sme-func-attrs-without-target-feature.cpp
@@ -0,0 +1,37 @@
+// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -target-feature +sve -fsyntax-only -verify %s
+
+// This test is testing the diagnostic that Clang emits when compiling without '+sme'.
+
+void streaming_compatible_def() __arm_streaming_compatible {} // OK
+void streaming_def() __arm_streaming { } // expected-error {{function executed in streaming-SVE mode or using ZA state, requires sme}}
+void shared_za_def() __arm_shared_za { } // expected-error {{function executed in streaming-SVE mode or using ZA state, requires sme}}
+__arm_new_za void new_za_def() { } // expected-error {{function executed in streaming-SVE mode or using ZA state, requires sme}}
+__arm_locally_streaming void locally_streaming_def() { } // expected-error {{function executed in streaming-SVE mode or using ZA state, requires sme}}
+
+// It should work fine when we explicitly add the target("sme") attribute.
+__attribute__((target("sme"))) void streaming_compatible_def_sme_attr() __arm_streaming_compatible {} // OK
+__attribute__((target("sme"))) void streaming_def_sme_attr() __arm_streaming { } // OK
+__attribute__((target("sme"))) void shared_za_def_sme_attr() __arm_shared_za { } // OK
+__arm_new_za __attribute__((target("sme"))) void new_za_def_sme_attr() {} // OK
+__arm_locally_streaming __attribute__((target("sme"))) void locally_streaming_def_sme_attr() {} // OK
+
+// No code is generated for declarations, so it should be fine to declare using the attribute.
+void streaming_compatible_decl() __arm_streaming_compatible; // OK
+void streaming_decl() __arm_streaming; // OK
+void shared_za_decl() __arm_shared_za; // OK
+
+void non_streaming_decl();
+void non_streaming_def() {
+ streaming_compatible_decl(); // OK
+ streaming_decl(); // expected-error {{call to a streaming function requires sme}}
+}
+
+void streaming_compatible_def2() {
+ non_streaming_decl(); // OK
+ streaming_compatible_decl(); // OK
+ streaming_decl(); // expected-error {{call to a streaming function requires sme}}
+}
+
+// Also test when call-site is not a function.
+int streaming_decl_ret_int() __arm_streaming;
+int x = streaming_decl_ret_int(); // expected-error {{call to a streaming function requires sme}}
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -12069,6 +12069,29 @@
if (!Redeclaration && LangOpts.CUDA)
checkCUDATargetOverload(NewFD, Previous);
}
+
+ // Check if the function definition uses any AArch64 SME features without
+ // having the '+sme' feature enabled.
+ if (DeclIsDefn) {
+ bool RequiresSME = NewFD->hasAttr<ArmLocallyStreamingAttr>() ||
+ NewFD->hasAttr<ArmNewZAAttr>();
+ if (!RequiresSME) {
+ if (const auto *FPT = NewFD->getType()->getAs<FunctionProtoType>()) {
+ FunctionProtoType::ExtProtoInfo EPI = FPT->getExtProtoInfo();
+ RequiresSME =
+ EPI.AArch64SMEAttributes & (FunctionType::SME_PStateSMEnabledMask |
+ FunctionType::SME_PStateZASharedMask);
+ }
+ }
+
+ if (RequiresSME) {
+ llvm::StringMap<bool> FeatureMap;
+ Context.getFunctionFeatureMap(FeatureMap, NewFD);
+ if (!FeatureMap.count("sme"))
+ Diag(NewFD->getLocation(), diag::err_sme_definition_in_non_sme_target);
+ }
+ }
+
return Redeclaration;
}
Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -6711,6 +6711,20 @@
ArgTy, ParamTy);
}
}
+
+ // If the callee has an AArch64 SME attribute to indicate that it is an
+ // __arm_streaming function, then the caller requires SME to be available.
+ FunctionProtoType::ExtProtoInfo ExtInfo = Proto->getExtProtoInfo();
+ if (ExtInfo.AArch64SMEAttributes & FunctionType::SME_PStateSMEnabledMask) {
+ if (auto *CallerFD = dyn_cast<FunctionDecl>(CurContext)) {
+ llvm::StringMap<bool> CallerFeatureMap;
+ Context.getFunctionFeatureMap(CallerFeatureMap, CallerFD);
+ if (!CallerFeatureMap.count("sme"))
+ Diag(Loc, diag::err_sme_call_in_non_sme_target);
+ } else if (!Context.getTargetInfo().hasFeature("sme")) {
+ Diag(Loc, diag::err_sme_call_in_non_sme_target);
+ }
+ }
}
if (FDecl && FDecl->hasAttr<AllocAlignAttr>()) {
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3624,6 +3624,10 @@
"the vecreturn attribute can only be used on a POD (plain old data) class or structure (i.e. no virtual functions)">;
def err_sme_attr_mismatch : Error<
"function declared %0 was previously declared %1, which has different SME function attributes">;
+def err_sme_call_in_non_sme_target : Error<
+ "call to a streaming function requires sme">;
+def err_sme_definition_in_non_sme_target : Error<
+ "function executed in streaming-SVE mode or using ZA state, requires sme">;
def err_cconv_change : Error<
"function declared '%0' here was previously declared "
"%select{'%2'|without calling convention}1">;
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