Ping http://gcc.gnu.org/ml/gcc-patches/2011-09/msg01002.html http://gcc.gnu.org/ml/gcc-patches/2011-09/msg01003.html and http://gcc.gnu.org/ml/gcc-patches/2011-09/msg01596.html
The last one needs a tweak. s/FUNCTION_VALUE_REGNO_P/targetm.calls.function_value_regno_p/, or wrap the whole patch in #ifdef FUNCTION_VALUE_REGNO_P. Perhaps I should explain more than what I wrote in the comment too. For targets like powerpc that pass function arguments in registers and return a function result in the same register as one of the arguments, the ifcvt optimization can prevent shrink wrapping. Without the ifcvt optimization for a function "int foo (int x)" we might have something like r29 = r3; // save r3 in callee saved reg if (some test) goto exit_label // main body of foo, calling other functions r3 = 0; return; exit_label: r3 = 1; return; Bernd's http://gcc.gnu.org/ml/gcc-patches/2011-10/msg00380.html quite happily rearranges the r29 assignment to be after the "if", and shrink wrapping occurs. With the ifcvt optimization we get r29 = r3; // save r3 in callee saved reg r3 = 1; if (some test) goto exit_label // main body of foo, calling other functions r3 = 0; exit_label: return; and now the r29 assignment cannot be moved past the "if", disabling shrink wrap. -- Alan Modra Australia Development Lab, IBM
