https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105638
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by H.J. Lu <h...@gcc.gnu.org>: https://gcc.gnu.org/g:a743a72714fc4a9d7036d28d0cacdf2a3621f629 commit r13-921-ga743a72714fc4a9d7036d28d0cacdf2a3621f629 Author: H.J. Lu <hjl.to...@gmail.com> Date: Wed May 18 13:00:47 2022 -0700 DSE: Use the constant store source if possible RTL DSE tracks redundant constant stores within a basic block. When RTL loop invariant motion hoists a constant initialization out of the loop into a separate basic block, the constant store value becomes unknown within the original basic block. When recording store for RTL DSE, check if the source register is set only once to a constant by a non-partial unconditional load. If yes, record the constant as the constant store source. It eliminates unrolled zero stores after memset 0 in a loop where a vector register is used as the zero store source. gcc/ PR rtl-optimization/105638 * df-core.cc (df_find_single_def_src): Moved and renamed from find_single_def_src in loop-iv.cc. Change the argument to rtx and use rtx_equal_p. Return null for partial or conditional defs. * df.h (df_find_single_def_src): New prototype. * dse.cc (record_store): Use the constant source if the source register is set only once. * loop-iv.cc (find_single_def_src): Moved to df-core.cc. (replace_single_def_regs): Replace find_single_def_src with df_find_single_def_src. gcc/testsuite/ PR rtl-optimization/105638 * g++.target/i386/pr105638.C: New test.
