Issue 27189: configure --with-lto with clang should find the appropriate llvm-profdata tool

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classification

Title:	configure --with-lto with clang should find the appropriate llvm-profdata tool
Type:	compile error	Stage:	needs patch
Components:	Build	Versions:	Python 3.6, Python 3.5, Python 2.7

process

Status:	open	Resolution:
Dependencies:		Superseder:
Assigned To:		Nosy List:	gregory.p.smith
Priority:	normal	Keywords:

Created on 2016-06-02 22:31 by gregory.p.smith, last changed 2022-04-11 14:58 by admin.

Messages (1)
msg266976 - (view)	Author: Gregory P. Smith (gregory.p.smith) *	Date: 2016-06-02 22:31
The --with-lto support added in issue25702 can work with clang, but on a Linux distribution such as ubuntu 16.04 with clang installed you get: $ CC=clang ./configure --with-lto ... $ make profile-opt Error: Cannot perform PGO build because llvm-profdata was not found in PATH Please add it to PATH and run ./configure again Makefile:503: recipe for target 'profile-opt' failed make: *** [profile-opt] Error 1 The llvm-profdata tool exists but is only known as llvm-profdata-3.8. We should have the ./configure script figure this out. I'm not sure what the preferred "right" way to determine this is. Detecting that CC is a clang compiler and using its reported version number? noticing that clang is a symlink into an llvm-X.Y tree and using that number? none of these sound great. hopefully there is a better deterministic way to query clang for this.

msg266976 - (view)

Author: Gregory P. Smith (gregory.p.smith) * (Python committer)

Date: 2016-06-02 22:31

The --with-lto support added in issue25702 can work with clang, but on a Linux distribution such as ubuntu 16.04 with clang installed you get:

$ CC=clang ./configure --with-lto
...
$ make profile-opt
Error: Cannot perform PGO build because llvm-profdata was not found in PATH
Please add it to PATH and run ./configure again
Makefile:503: recipe for target 'profile-opt' failed
make: *** [profile-opt] Error 1

The llvm-profdata tool exists but is only known as llvm-profdata-3.8.  We should have the ./configure script figure this out.  I'm not sure what the preferred "right" way to determine this is.  Detecting that CC is a clang compiler and using its reported version number?  noticing that clang is a symlink into an llvm-X.Y tree and using that number?  none of these sound great.  hopefully there is a better deterministic way to query clang for this.

History
Date	User	Action	Args
2022-04-11 14:58:31	admin	set	github: 71376
2016-06-02 22:31:55	gregory.p.smith	create