Add a new function attribute, 'alignstack'. It will indicate (when the backends

implement support for it) that the stack should be forcibly realigned in the
prologue (and the process reversed in the epilogue).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95945 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 34 insertions, 0 deletions

diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 5dd6569..4dab118 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -956,6 +956,14 @@ bool LLParser::ParseOptionalAttrs(unsigned &Attrs, unsigned AttrKind) {
     case lltok::kw_noimplicitfloat: Attrs |= Attribute::NoImplicitFloat; break;
     case lltok::kw_naked:           Attrs |= Attribute::Naked; break;
 
+    case lltok::kw_alignstack: {
+      unsigned Alignment;
+      if (ParseOptionalStackAlignment(Alignment))
+        return true;
+      Attrs |= Attribute::constructStackAlignmentFromInt(Alignment);
+      continue;
+    }
+
     case lltok::kw_align: {
       unsigned Alignment;
       if (ParseOptionalAlignment(Alignment))
@@ -963,6 +971,7 @@ bool LLParser::ParseOptionalAttrs(unsigned &Attrs, unsigned AttrKind) {
       Attrs |= Attribute::constructAlignmentFromInt(Alignment);
       continue;
     }
+
     }
     Lex.Lex();
   }
@@ -1131,6 +1140,25 @@ bool LLParser::ParseOptionalCommaAlign(unsigned &Alignment,
   return false;
 }
 
+/// ParseOptionalStackAlignment
+///   ::= /* empty */
+///   ::= 'alignstack' '(' 4 ')'
+bool LLParser::ParseOptionalStackAlignment(unsigned &Alignment) {
+  Alignment = 0;
+  if (!EatIfPresent(lltok::kw_alignstack))
+    return false;
+  LocTy ParenLoc = Lex.getLoc();
+  if (!EatIfPresent(lltok::lparen))
+    return Error(ParenLoc, "expected '('");
+  LocTy AlignLoc = Lex.getLoc();
+  if (ParseUInt32(Alignment)) return true;
+  ParenLoc = Lex.getLoc();
+  if (!EatIfPresent(lltok::rparen))
+    return Error(ParenLoc, "expected ')'");
+  if (!isPowerOf2_32(Alignment))
+    return Error(AlignLoc, "stack alignment is not a power of two");
+  return false;
+}
 
 /// ParseIndexList - This parses the index list for an insert/extractvalue
 /// instruction.  This sets AteExtraComma in the case where we eat an extra
diff --git a/lib/AsmParser/LLParser.h b/lib/AsmParser/LLParser.h
index 85c07ff..ed7a1d7 100644
--- a/lib/AsmParser/LLParser.h
+++ b/lib/AsmParser/LLParser.h
@@ -169,6 +169,7 @@ namespace llvm {
     bool ParseOptionalVisibility(unsigned &Visibility);
     bool ParseOptionalCallingConv(CallingConv::ID &CC);
     bool ParseOptionalAlignment(unsigned &Alignment);
+    bool ParseOptionalStackAlignment(unsigned &Alignment);
     bool ParseInstructionMetadata(SmallVectorImpl<std::pair<unsigned,
                                                             MDNode *> > &);
     bool ParseOptionalCommaAlign(unsigned &Alignment, bool &AteExtraComma);
diff --git a/lib/VMCore/Attributes.cpp b/lib/VMCore/Attributes.cpp
index a371c6f..6fa597e 100644
--- a/lib/VMCore/Attributes.cpp
+++ b/lib/VMCore/Attributes.cpp
@@ -70,6 +70,11 @@ std::string Attribute::getAsString(Attributes Attrs) {
     Result += "noimplicitfloat ";
   if (Attrs & Attribute::Naked)
     Result += "naked ";
+  if (Attrs & Attribute::StackAlignment) {
+    Result += "alignstack(";
+    Result += utostr(Attribute::getStackAlignmentFromAttrs(Attrs));
+    Result += ") ";
+  }
   if (Attrs & Attribute::Alignment) {
     Result += "align ";
     Result += utostr(Attribute::getAlignmentFromAttrs(Attrs));