Author: baldrick
Date: Sun Jan 27 12:11:13 2008
New Revision: 46415
URL: http://llvm.org/viewvc/llvm-project?rev=46415&view=rev
Log:
Do not mark a function readnone or readonly if it has
a byval parameter.
Modified:
llvm-gcc-4.2/trunk/gcc/llvm-types.cpp
Modified: llvm-gcc-4.2/trunk/gcc/llvm-types.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/llvm-types.cpp?rev=46415&r1=46414&r2=46415&view=diff
==============================================================================
--- llvm-gcc-4.2/trunk/gcc/llvm-types.cpp (original)
+++ llvm-gcc-4.2/trunk/gcc/llvm-types.cpp Sun Jan 27 12:11:13 2008
@@ -1219,14 +1219,19 @@
DeclArgs = TREE_CHAIN(DeclArgs);
}
- // If we see a byval argument and if the function is 'readnone' we have to
- // demote the function to being 'readonly' instead. Not doing so would allow
- // optimizers to delete stores into the argument that is passed into the
- // function.
- if (HasByVal && Attrs[0].index == 0 &&
- (Attrs[0].attrs & ParamAttr::ReadNone)) {
- Attrs[0].attrs &= ~ParamAttr::ReadNone;
- Attrs[0].attrs |= ParamAttr::ReadOnly;
+ // If there is a byval argument then it is not safe to mark the function
+ // 'readnone' or 'readonly': gcc permits a 'const' or 'pure' function to
+ // write to struct arguments passed by value, but in LLVM this becomes a
+ // write through the byval pointer argument, which LLVM does not allow for
+ // readonly/readnone functions.
+ if (HasByVal && Attrs[0].index == 0) {
+ uint16_t &RAttrs = Attrs[0].attrs;
+ RAttrs &= ~(ParamAttr::ReadNone | ParamAttr::ReadOnly);
+ if (RAttrs == ParamAttr::None) {
+ for (unsigned i = 1, e = Attrs.size(); i < e ; ++i)
+ Attrs[i-1] = Attrs[i];
+ Attrs.pop_back();
+ }
}
// If the argument list ends with a void type node, it isn't vararg.
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