Propagate the AlignStack bit in InlineAsm's to the

PrologEpilog code, and use it to determine whether
the asm forces stack alignment or not.  gcc consistently
does not do this for GCC-style asms; Apple gcc inconsistently
sometimes does it for asm blocks.  There is no
convenient place to put a bit in either the SDNode or
the MachineInstr form, so I've added an extra operand
to each; unlovely, but it does allow for expansion for
more bits, should we need it.  PR 5125.  Some
existing testcases are affected.
The operand lists of the SDNode and MachineInstr forms
are indexed with awesome mnemonics, like "2"; I may
fix this someday, but not now.  I'm not making it any
worse.  If anyone is inspired I think you can find all
the right places from this patch.

llvm-svn: 107506

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index e92b44fcff1..62b7c21cc8a 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -158,9 +158,9 @@ void PEI::calculateCallsInformation(MachineFunction &Fn) {
         AdjustsStack = true;
         FrameSDOps.push_back(I);
       } else if (I->isInlineAsm()) {
-        // An InlineAsm might be a call; assume it is to get the stack frame
-        // aligned correctly for calls.
-        AdjustsStack = true;
+        // Some inline asm's need a stack frame, as indicated by operand 1.
+        if (I->getOperand(1).getImm())
+          AdjustsStack = true;
       }
 
   MFI->setAdjustsStack(AdjustsStack);