https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
Bug ID: 82365
Summary: excessive stack usage with norreturn attribute
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: other
Assignee: unassigned at gcc dot gnu.org
Reporter: clyon at gcc dot gnu.org
Target Milestone: ---
Created attachment 42264
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42264&action=edit
testcase
We have noticed that gcc fails to reuse stack locations in presence of noreturn
attribute in the call graph.
Basically, the attached testcase has
case 1: { struct XXX localvar; bla1; break; }
case 2: { struct XXX localvar; bla2; break; }
case 3: { struct XXX localvar; bal3; break; }
With noreturn attribute:
aarch64-linux-gnu-gcc -Wall -O2 -S bz-3265.c --param asan-stack=1
-Wframe-larger-than=1
bz-3265.c: In function ‘em28xx_dvb_init’:
bz-3265.c:99:1: warning: the frame size of 480 bytes is larger than 1 bytes
[-Wframe-larger-than=]
Without noreturn attribute:
aarch64-linux-gnu-gcc -Wall -O2 -S bz-3265.c --param asan-stack=1
-Wframe-larger-than=1 -DNONORETURN
bz-3265.c: In function ‘em28xx_dvb_init’:
bz-3265.c:99:1: warning: the frame size of 128 bytes is larger than 1 bytes
[-Wframe-larger-than=]
The code fragment is extracted from the linux kernel where this causes more
problems with using -fsanitize=kernel-address, where this causes excessive
stack usage.
I used an aarch64 compiler here, but Arnd observed similar problems on x86_64
too.
