https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121444
Bug ID: 121444
Summary: [16 Regression] nvptx: Increased '.align' for 'CSWTCH'
after "Improve mergability of CSWTCH [PR120523]"
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: tschwinge at gcc dot gnu.org
CC: pinskia at gcc dot gnu.org, vries at gcc dot gnu.org
Target Milestone: ---
Target: nvptx
For nvptx, I'm seeing increased '.align' for 'CSWTCH'es after commit
r16-2595-gf1c8014764178335e3b949e06b894ff5775beae5 "Improve mergability of
CSWTCH [PR120523]", for example:
--- "0-wo_Improve mergability of CSWTCH
[PR120523]/nvptx-none/newlib/libm/math/libm_a-e_atan2.o" 2025-08-04
17:15:09.921571480 +0200
+++ "1-w_Improve mergability of CSWTCH
[PR120523]/nvptx-none/newlib/libm/math/libm_a-e_atan2.o" 2025-08-06
11:38:01.766996470 +0200
@@ -14,6 +14,6 @@
// BEGIN VAR DEF: CSWTCH$7
-.global .align 8 .u64 CSWTCH$7[3] =
+.global .align 32 .u64 CSWTCH$7[3] =
{-9223372036854775808,4614256656552045848,-4609115380302729960 };
// BEGIN VAR DEF: CSWTCH$6
-.global .align 8 .u64 CSWTCH$6[3] =
+.global .align 32 .u64 CSWTCH$6[3] =
{-4618122579557470952,4612488097114038738,-4610883939740737070 };
--- "0-wo_Improve mergability of CSWTCH
[PR120523]/nvptx-none/newlib/libm/math/libm_a-ef_atan2.o" 2025-08-04
17:15:10.049570119 +0200
+++ "1-w_Improve mergability of CSWTCH
[PR120523]/nvptx-none/newlib/libm/math/libm_a-ef_atan2.o" 2025-08-06
11:38:01.834995725 +0200
@@ -14,6 +14,6 @@
// BEGIN VAR DEF: CSWTCH$7
-.global .align 4 .u32 CSWTCH$7[3] =
+.global .align 16 .u32 CSWTCH$7[3] =
{2147483648,1078530011,3226013659 };
// BEGIN VAR DEF: CSWTCH$6
-.global .align 4 .u32 CSWTCH$6[3] =
+.global .align 16 .u32 CSWTCH$6[3] =
{3209236443,1075235812,3222719460 };
Per my understanding, that shouldn't be necessary; "The default alignment for
scalar and array variables is to a multiple of the base-type size." (as it got
emitted before, explicitly: 'u32' -> 'align 4', etc.).
I've not yet attempted to understand whether that's a generic or nvptx-specific
issue.
