MSVC doesn't support adding alignment to functions, so create a separ…

…ate #define for this, which is a no-op on MSVC Given that this occurs in several tests, and the MSVC tests have error-on-warning, this is a comment rather than a #warning
JuliaHubOSS · Jan 13, 2024 · 0f410a3 · 0f410a3
1 parent 8c4c719
commit 0f410a3
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Showing 3 changed files with 28 additions and 7 deletions.
diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
@@ -2051,6 +2051,14 @@ static void defineAligns(raw_ostream &Out) {
   Out << "#endif\n\n";
 }
 
+static void defineFunctionAlign(raw_ostream &Out) {
+  Out << "#ifdef _MSC_VER\n";
+  Out << "#define __FUNCTIONALIGN__(X) /* WARNING: THIS FEATURE IS NOT SUPPORTED BY MSVC! */ \n";
+  Out << "#else\n";
+  Out << "#define __FUNCTIONALIGN__(X) __attribute__((aligned(X)))\n";
+  Out << "#endif\n\n";
+}
+
 static void defineUnreachable(raw_ostream &Out) {
   Out << "#ifdef _MSC_VER\n";
   Out << "#define __builtin_unreachable() __assume(0)\n";
@@ -2340,6 +2348,8 @@ void CWriter::generateCompilerSpecificCode(raw_ostream &Out,
     defineUnalignedLoad(Out);
   if (headerIncAligns())
     defineAligns(Out);
+  if (headerIncFunctionAlign())
+    defineFunctionAlign(Out);
   if (headerIncNanInf())
     defineNanInf(Out);
   if (headerIncInt128())
@@ -2610,12 +2620,6 @@ void CWriter::generateHeader(Module &M) {
       Out << "__MSVC_INLINE__ ";
     }
 
-    unsigned Alignment = I->getAlignment();
-    if (Alignment != 0) {
-      headerUseAligns();
-      Out << "__PREFIXALIGN__(" << Alignment << ") ";
-    }
-
     printFunctionProto(Out, &*I, GetValueName(&*I));
     printFunctionAttributes(Out, I->getAttributes());
     if (I->hasWeakLinkage() || I->hasLinkOnceLinkage()) {
@@ -2635,8 +2639,10 @@ void CWriter::generateHeader(Module &M) {
       Out << " __HIDDEN__";
     }
 
+    unsigned Alignment = I->getAlignment();
     if (Alignment != 0) {
-      Out << " __POSTFIXALIGN__(" << Alignment << ")";
+      headerUseFunctionAlign();
+      Out << " __FUNCTIONALIGN__(" << Alignment << ") ";
     }
 
     if (I->hasName() && I->getName()[0] == 1)

diff --git a/lib/Target/CBackend/CBackend.h b/lib/Target/CBackend/CBackend.h
@@ -112,6 +112,7 @@ class CWriter : public FunctionPass, public InstVisitor<CWriter> {
     bool AttributeList : 1;
     bool UnalignedLoad : 1;
     bool Aligns : 1;
+    bool FunctionAlign : 1;
     bool NanInf : 1;
     bool Int128 : 1;
     bool ThreadFence : 1;
@@ -121,6 +122,7 @@ class CWriter : public FunctionPass, public InstVisitor<CWriter> {
     bool ConstantFP80Ty : 1;
     bool ConstantFP128Ty : 1;
     bool ForceInline : 1;
+    bool Trap : 1;
   } UsedHeaders;
 
 #define USED_HEADERS_FLAG(Name)                                                \
@@ -146,6 +148,7 @@ class CWriter : public FunctionPass, public InstVisitor<CWriter> {
   USED_HEADERS_FLAG(AttributeList)
   USED_HEADERS_FLAG(UnalignedLoad)
   USED_HEADERS_FLAG(Aligns)
+  USED_HEADERS_FLAG(FunctionAlign)
   USED_HEADERS_FLAG(NanInf)
   USED_HEADERS_FLAG(Int128)
   USED_HEADERS_FLAG(ThreadFence)
@@ -155,6 +158,7 @@ class CWriter : public FunctionPass, public InstVisitor<CWriter> {
   USED_HEADERS_FLAG(ConstantFP80Ty)
   USED_HEADERS_FLAG(ConstantFP128Ty)
   USED_HEADERS_FLAG(ForceInline)
+  USED_HEADERS_FLAG(Trap)
 
   llvm::SmallSet<CmpInst::Predicate, 26> FCmpOps;
   void headerUseFCmpOp(CmpInst::Predicate P);

diff --git a/test/cpp_tests/test_virtual_function_calls.cpp b/test/cpp_tests/test_virtual_function_calls.cpp
@@ -1,3 +1,4 @@
+#ifndef _MSC_VER
 struct A {
   int a;
   int b;
@@ -17,3 +18,13 @@ int main() {
     return 0;
   return 6;
 }
+
+#else
+
+/* MSVC doesn't support adding alignment to functions, treat it as an expected failure */
+
+int main() {
+  return 25;
+}
+
+#endif