[llvm-commits] [PATCH] - Bug 8621 - inline asm - please review

[John Thompson]

>From my comment to the bug:

It looks like a problem with the back end.

I reduced the test case to:

void func()
{
  unsigned int src = 0, dst = 0;
  static const unsigned long flagmask = 1;
  unsigned long flags = 1;
  unsigned long newflags = ~(0UL);
  asm (
    "pushfq \n"
    "andq %2, (%%rsp) \n"
    "orq  %3, (%%rsp) \n"
    "popfq \n"
    "addb %4, %1 \n"
    "pushfq \n"
    "popq %0 \n"
       :
          "=&rm" (newflags) ,
          "=&rm" (*(unsigned char *)&dst)
       :
          "i" (~flagmask) ,
          "r" (flags & flagmask) ,
          "r" (*(unsigned char *)&src) ,
          "1" (*(unsigned char *)&dst)
       : "cc");
}

The constraints involved in the problem are index 1 and 5, which we see do
match types in the above code.

This change seems to fix it:

Index: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (revision 119175)
+++ lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (working copy)
@@ -5545,9 +5545,6 @@
     // If this is an input or an indirect output, process the call
argument.
     // BasicBlocks are labels, currently appearing only in asm's.
     if (OpInfo.CallOperandVal) {
-      // Strip bitcasts, if any.  This mostly comes up for functions.
-      OpInfo.CallOperandVal = OpInfo.CallOperandVal->stripPointerCasts();
-
       if (const BasicBlock *BB =
dyn_cast<BasicBlock>(OpInfo.CallOperandVal)) {
         OpInfo.CallOperand = DAG.getBasicBlock(FuncInfo.MBBMap[BB]);
       } else {

The removed code apparently was stripping the pointer cast.  I don't know
the original reason for it.

I ran the LLVM regression tests, test suite, and gcc tests, with no
differences.  Does this seem like the correct fix?  If so, let me know and
I'll check this in.  Or was there a reason for the cast stripping?

It doesn't appear to be related to my inline asm work.

-John


-- 
John Thompson
John.Thompson.JTSoftware at gmail.com
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