RFC: redundant stores in C++

[Dale Johannesen <dalej at apple dot com>]

In C++, when we have an automatic array with variable initializers:

void bar(char[4]);
void foo(char a, char b, char c, char d) {
  char x[4] = { a, b, c, d };
  bar(x);
}

the C++ FE generates 32-bit store(s) of 0 for the entire array, 
followed by stores
of the individual elements.  In the case above, where the elements are 
not
32-bits, the optimizers do not figure out they can eliminate the 
redundant store(s)
of 0.  The C FE does not generate that to begin with, and the C++ FE 
should
not either.   This is not my native habitat, but I think this is the 
right general idea:

Attachment: diffs4.txt
Description: Text document

Testsuite passes with this but I can believe improvements are possible; 
comments?