http://llvm.org/bugs/show_bug.cgi?id=14697
Bug #: 14697
Summary: clang doesn't pass target CPU to linker command for
LTO
Product: clang
Version: 3.2
Platform: PC
OS/Version: Linux
Status: NEW
Severity: normal
Priority: P
Component: Driver
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
Classification: Unclassified
Created attachment 9756
--> http://llvm.org/bugs/attachment.cgi?id=9756
test.c
Clang should pass the chosen target CPU (e.g. -march option) to the linker for
LTO. Currently the target CPU is not passed, which makes LTO assume the target
CPU is "native", i.e. current CPU. This sometimes results in the emitting of
instructions not supported based on the -march option.
To reproduce this problem:
1) Compile the attached C program, on a new CPU which supports 'vxorps' (in my
case, Core i3 2120). Make sure the gold linker is being used. Compile with this
command:
clang -### -g -march=corei7 -O4 -flto test.c -o test
Attached is compiler output. See how corei7 is not being passed to the linker.
2) Disassemble the resulting program (objdump -S test) and notice the 'vxorps'
instruction which should not have been emitted. Disassembly is attached.
Alternatively, run the program on an older Core i7 CPU and see it crash with
SIGILL.
--
Configure bugmail: http://llvm.org/bugs/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.
_______________________________________________
LLVMbugs mailing list
[email protected]
http://lists.cs.uiuc.edu/mailman/listinfo/llvmbugs
