[AArch64] NFC: Simplify discombobulating 'requiresSMChange' interface

[sdesmalen-arm]

Having it return a std::optional<bool> is unnecessarily confusing. This patch changes it to a simple 'bool'.

This patch also removes the 'BodyOverridesInterface' operand because there is only a single use for this which is easily rewritten.

[llvmbot]

@llvm/pr-subscribers-backend-aarch64

Author: Sander de Smalen (sdesmalen-arm)

Changes

Having it return a std::optional<bool> is unnecessarily confusing. This patch changes it to a simple 'bool'.

This patch also removes the 'BodyOverridesInterface' operand because there is only a single use for this which is easily rewritten.

---

Full diff: https://github.com/llvm/llvm-project/pull/78703.diff

5 Files Affected:

• (modified) llvm/lib/Target/AArch64/AArch64ISelLowering.cpp (+7-8)
• (modified) llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp (+3-2)
• (modified) llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.cpp (+5-15)
• (modified) llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.h (+1-8)
• (modified) llvm/unittests/Target/AArch64/SMEAttributesTest.cpp (+12-47)

diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 8a6f1dc7487bae8..b0548cc64fcf319 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -7650,8 +7650,7 @@ AArch64TargetLowering::LowerCall(CallLoweringInfo &CLI,
   }
 
   SDValue PStateSM;
-  std::optional<bool> RequiresSMChange =
-      CallerAttrs.requiresSMChange(CalleeAttrs);
+  bool RequiresSMChange = CallerAttrs.requiresSMChange(CalleeAttrs);
   if (RequiresSMChange) {
     if (CallerAttrs.hasStreamingInterfaceOrBody())
       PStateSM = DAG.getConstant(1, DL, MVT::i64);
@@ -7925,8 +7924,9 @@ AArch64TargetLowering::LowerCall(CallLoweringInfo &CLI,
 
   SDValue InGlue;
   if (RequiresSMChange) {
-    SDValue NewChain = changeStreamingMode(DAG, DL, *RequiresSMChange, Chain,
-                                           InGlue, PStateSM, true);
+    SDValue NewChain =
+        changeStreamingMode(DAG, DL, CalleeAttrs.hasStreamingInterface(), Chain,
+                            InGlue, PStateSM, true);
     Chain = NewChain.getValue(0);
     InGlue = NewChain.getValue(1);
   }
@@ -8076,8 +8076,8 @@ AArch64TargetLowering::LowerCall(CallLoweringInfo &CLI,
 
   if (RequiresSMChange) {
     assert(PStateSM && "Expected a PStateSM to be set");
-    Result = changeStreamingMode(DAG, DL, !*RequiresSMChange, Result, InGlue,
-                                 PStateSM, false);
+    Result = changeStreamingMode(DAG, DL, !CalleeAttrs.hasStreamingInterface(),
+                                 Result, InGlue, PStateSM, false);
   }
 
   if (RequiresLazySave) {
@@ -25479,8 +25479,7 @@ bool AArch64TargetLowering::fallBackToDAGISel(const Instruction &Inst) const {
   if (auto *Base = dyn_cast<CallBase>(&Inst)) {
     auto CallerAttrs = SMEAttrs(*Inst.getFunction());
     auto CalleeAttrs = SMEAttrs(*Base);
-    if (CallerAttrs.requiresSMChange(CalleeAttrs,
-                                     /*BodyOverridesInterface=*/false) ||
+    if (CallerAttrs.requiresSMChange(CalleeAttrs) ||
         CallerAttrs.requiresLazySave(CalleeAttrs))
       return true;
   }
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index d358a5c8bd9499f..08ae536fe9bbf0e 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -236,8 +236,9 @@ bool AArch64TTIImpl::areInlineCompatible(const Function *Caller,
     return false;
 
   if (CallerAttrs.requiresLazySave(CalleeAttrs) ||
-      CallerAttrs.requiresSMChange(CalleeAttrs,
-                                   /*BodyOverridesInterface=*/true)) {
+      (CallerAttrs.requiresSMChange(CalleeAttrs) &&
+       (!CallerAttrs.hasStreamingInterfaceOrBody() ||
+        !CalleeAttrs.hasStreamingBody()))) {
     if (hasPossibleIncompatibleOps(Callee))
       return false;
   }
diff --git a/llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.cpp b/llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.cpp
index ccdec78d7808663..9693b6a664be262 100644
--- a/llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.cpp
+++ b/llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.cpp
@@ -82,27 +82,17 @@ SMEAttrs::SMEAttrs(const AttributeList &Attrs) {
     Bitmask |= encodeZT0State(StateValue::New);
 }
 
-std::optional<bool>
-SMEAttrs::requiresSMChange(const SMEAttrs &Callee,
-                           bool BodyOverridesInterface) const {
-  // If the transition is not through a call (e.g. when considering inlining)
-  // and Callee has a streaming body, then we can ignore the interface of
-  // Callee.
-  if (BodyOverridesInterface && Callee.hasStreamingBody()) {
-    return hasStreamingInterfaceOrBody() ? std::nullopt
-                                         : std::optional<bool>(true);
-  }
-
+bool SMEAttrs::requiresSMChange(const SMEAttrs &Callee) const {
   if (Callee.hasStreamingCompatibleInterface())
-    return std::nullopt;
+    return false;
 
   // Both non-streaming
   if (hasNonStreamingInterfaceAndBody() && Callee.hasNonStreamingInterface())
-    return std::nullopt;
+    return false;
 
   // Both streaming
   if (hasStreamingInterfaceOrBody() && Callee.hasStreamingInterface())
-    return std::nullopt;
+    return false;
 
-  return Callee.hasStreamingInterface();
+  return true;
 }
diff --git a/llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.h b/llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.h
index af2854856fb9796..6f622f1996a3a0a 100644
--- a/llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.h
+++ b/llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.h
@@ -75,14 +75,7 @@ class SMEAttrs {
 
   /// \return true if a call from Caller -> Callee requires a change in
   /// streaming mode.
-  /// If \p BodyOverridesInterface is true and Callee has a streaming body,
-  /// then requiresSMChange considers a call to Callee as having a Streaming
-  /// interface. This can be useful when considering e.g. inlining, where we
-  /// explicitly want the body to overrule the interface (because after inlining
-  /// the interface is no longer relevant).
-  std::optional<bool>
-  requiresSMChange(const SMEAttrs &Callee,
-                   bool BodyOverridesInterface = false) const;
+  bool requiresSMChange(const SMEAttrs &Callee) const;
 
   // Interfaces to query PSTATE.ZA
   bool hasNewZABody() const { return Bitmask & ZA_New; }
diff --git a/llvm/unittests/Target/AArch64/SMEAttributesTest.cpp b/llvm/unittests/Target/AArch64/SMEAttributesTest.cpp
index 2f7201464ba2f23..294e5571814246a 100644
--- a/llvm/unittests/Target/AArch64/SMEAttributesTest.cpp
+++ b/llvm/unittests/Target/AArch64/SMEAttributesTest.cpp
@@ -193,86 +193,51 @@ TEST(SMEAttributes, Transitions) {
   ASSERT_FALSE(SA(SA::Normal).requiresSMChange(SA(SA::Normal)));
   // Normal -> Normal + LocallyStreaming
   ASSERT_FALSE(SA(SA::Normal).requiresSMChange(SA(SA::Normal | SA::SM_Body)));
-  ASSERT_EQ(*SA(SA::Normal)
-                 .requiresSMChange(SA(SA::Normal | SA::SM_Body),
-                                   /*BodyOverridesInterface=*/true),
-            true);
 
   // Normal -> Streaming
-  ASSERT_EQ(*SA(SA::Normal).requiresSMChange(SA(SA::SM_Enabled)), true);
+  ASSERT_TRUE(SA(SA::Normal).requiresSMChange(SA(SA::SM_Enabled)));
   // Normal -> Streaming + LocallyStreaming
-  ASSERT_EQ(*SA(SA::Normal).requiresSMChange(SA(SA::SM_Enabled | SA::SM_Body)),
-            true);
-  ASSERT_EQ(*SA(SA::Normal)
-                 .requiresSMChange(SA(SA::SM_Enabled | SA::SM_Body),
-                                   /*BodyOverridesInterface=*/true),
-            true);
+  ASSERT_TRUE(
+      SA(SA::Normal).requiresSMChange(SA(SA::SM_Enabled | SA::SM_Body)));
 
   // Normal -> Streaming-compatible
   ASSERT_FALSE(SA(SA::Normal).requiresSMChange(SA(SA::SM_Compatible)));
   // Normal -> Streaming-compatible + LocallyStreaming
   ASSERT_FALSE(
       SA(SA::Normal).requiresSMChange(SA(SA::SM_Compatible | SA::SM_Body)));
-  ASSERT_EQ(*SA(SA::Normal)
-                 .requiresSMChange(SA(SA::SM_Compatible | SA::SM_Body),
-                                   /*BodyOverridesInterface=*/true),
-            true);
 
   // Streaming -> Normal
-  ASSERT_EQ(*SA(SA::SM_Enabled).requiresSMChange(SA(SA::Normal)), false);
+  ASSERT_TRUE(SA(SA::SM_Enabled).requiresSMChange(SA(SA::Normal)));
   // Streaming -> Normal + LocallyStreaming
-  ASSERT_EQ(*SA(SA::SM_Enabled).requiresSMChange(SA(SA::Normal | SA::SM_Body)),
-            false);
-  ASSERT_FALSE(SA(SA::SM_Enabled)
-                   .requiresSMChange(SA(SA::Normal | SA::SM_Body),
-                                     /*BodyOverridesInterface=*/true));
+  ASSERT_TRUE(
+      SA(SA::SM_Enabled).requiresSMChange(SA(SA::Normal | SA::SM_Body)));
 
   // Streaming -> Streaming
   ASSERT_FALSE(SA(SA::SM_Enabled).requiresSMChange(SA(SA::SM_Enabled)));
   // Streaming -> Streaming + LocallyStreaming
   ASSERT_FALSE(
       SA(SA::SM_Enabled).requiresSMChange(SA(SA::SM_Enabled | SA::SM_Body)));
-  ASSERT_FALSE(SA(SA::SM_Enabled)
-                   .requiresSMChange(SA(SA::SM_Enabled | SA::SM_Body),
-                                     /*BodyOverridesInterface=*/true));
 
   // Streaming -> Streaming-compatible
   ASSERT_FALSE(SA(SA::SM_Enabled).requiresSMChange(SA(SA::SM_Compatible)));
   // Streaming -> Streaming-compatible + LocallyStreaming
   ASSERT_FALSE(
       SA(SA::SM_Enabled).requiresSMChange(SA(SA::SM_Compatible | SA::SM_Body)));
-  ASSERT_FALSE(SA(SA::SM_Enabled)
-                   .requiresSMChange(SA(SA::SM_Compatible | SA::SM_Body),
-                                     /*BodyOverridesInterface=*/true));
 
   // Streaming-compatible -> Normal
-  ASSERT_EQ(*SA(SA::SM_Compatible).requiresSMChange(SA(SA::Normal)), false);
-  ASSERT_EQ(
-      *SA(SA::SM_Compatible).requiresSMChange(SA(SA::Normal | SA::SM_Body)),
-      false);
-  ASSERT_EQ(*SA(SA::SM_Compatible)
-                 .requiresSMChange(SA(SA::Normal | SA::SM_Body),
-                                   /*BodyOverridesInterface=*/true),
-            true);
+  ASSERT_TRUE(SA(SA::SM_Compatible).requiresSMChange(SA(SA::Normal)));
+  ASSERT_TRUE(
+      SA(SA::SM_Compatible).requiresSMChange(SA(SA::Normal | SA::SM_Body)));
 
   // Streaming-compatible -> Streaming
-  ASSERT_EQ(*SA(SA::SM_Compatible).requiresSMChange(SA(SA::SM_Enabled)), true);
+  ASSERT_TRUE(SA(SA::SM_Compatible).requiresSMChange(SA(SA::SM_Enabled)));
   // Streaming-compatible -> Streaming + LocallyStreaming
-  ASSERT_EQ(
-      *SA(SA::SM_Compatible).requiresSMChange(SA(SA::SM_Enabled | SA::SM_Body)),
-      true);
-  ASSERT_EQ(*SA(SA::SM_Compatible)
-                 .requiresSMChange(SA(SA::SM_Enabled | SA::SM_Body),
-                                   /*BodyOverridesInterface=*/true),
-            true);
+  ASSERT_TRUE(
+      SA(SA::SM_Compatible).requiresSMChange(SA(SA::SM_Enabled | SA::SM_Body)));
 
   // Streaming-compatible -> Streaming-compatible
   ASSERT_FALSE(SA(SA::SM_Compatible).requiresSMChange(SA(SA::SM_Compatible)));
   // Streaming-compatible -> Streaming-compatible + LocallyStreaming
   ASSERT_FALSE(SA(SA::SM_Compatible)
                    .requiresSMChange(SA(SA::SM_Compatible | SA::SM_Body)));
-  ASSERT_EQ(*SA(SA::SM_Compatible)
-                 .requiresSMChange(SA(SA::SM_Compatible | SA::SM_Body),
-                                   /*BodyOverridesInterface=*/true),
-            true);
 }

[MDevereau]

This looks much clearer now, thanks.