https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96767
Bug ID: 96767
Summary: -mpure-code produces indirect loads for thumb-1
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: clyon at gcc dot gnu.org
Target Milestone: ---
As described in PR94538, -mpure-code produces suboptimal code for thumb-1 CPUs.
int x;
int f1 (void) { return x; }
Compiled with -O2 -mpure-code,
-mcpu=cortex-m0:
movs r3, #:upper8_15:#.LC0
lsls r3, #8
adds r3, #:upper0_7:#.LC0
lsls r3, #8
adds r3, #:lower8_15:#.LC0
lsls r3, #8
adds r3, #:lower0_7:#.LC0
@ sp needed
ldr r3, [r3]
ldr r0, [r3]
bx lr
-> extra indirection, there should be only one ldr
For reference, -mcpu=cortex-m[347] and m23 produce:
movw r3, #:lower16:.LANCHOR0
movt r3, #:upper16:.LANCHOR0
ldr r0, [r3]
bx lr
