http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52415
Bug #: 52415 Summary: memcpy to local variable generates unnecessary stack frame for armv7 Classification: Unclassified Product: gcc Version: unknown Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: target AssignedTo: unassig...@gcc.gnu.org ReportedBy: jay.f...@gmail.com This test case uses memcpy to load the bytes of a float into an int: $ cat m.c int f(float *p) { int i; __builtin_memcpy(&i, p, sizeof i); return i; } When compiled for armv7 I get: $ cc1 -o - -O3 m.c -quiet -march=armv7 -mthumb ... f: @ args = 0, pretend = 0, frame = 4 @ frame_needed = 0, uses_anonymous_args = 0 @ link register save eliminated. ldr r0, [r0, #0] @ unaligned sub sp, sp, #4 str r0, [sp, #0] @ unaligned ldr r0, [sp, #0] add sp, sp, #4 bx lr ... The stack frame is unnecessary; it could compile to just: ldr r0, [r0, #0] bx lr I'm using trunk rev 184597, configured with --target=arm-elf.