Hi,
The RTL cprop pass in GCC operates by doing a local constant/copy propagation first and then a global one. In the local one, if a constant cannot be propagated (eg. due to constraints of the destination instruction) a copy propagation is done instead. However, at the global level copy propagation is only tried if no constant can be propagated, ie. if a constant can be propagated but the constraints of the destination instruction forbids it, no copy propagation will be tried. This patch fixes this issue. This solves the redundant ldr problem in GCC32RM-439.
ChangeLog entries are as follows:
*** gcc/ChangeLog ***
2015-01-21 Thomas Preud'homme thomas.preudhomme@arm.com
* cprop.c (find_avail_set): Return up to two sets, one whose source is
a register and one whose source is a constant. Sets are returned in
an array passed as parameter rather than as a return value.
(cprop_insn): Use a do while loop rather than a goto. Try each of the
sets returned by find_avail_set, starting with the one whose source is
a constant.
*** gcc/testsuite/ChangeLog ***
2015-01-21 Thomas Preud'homme thomas.preudhomme@arm.com
* gcc.target/arm/pr64616.c: New file.