[llvm-bugs] [Bug 39679] New: Disabling fp-contraction doesn't work. [#pragma clang fp contract(off)]

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=39679

            Bug ID: 39679
           Summary: Disabling fp-contraction doesn't work. [#pragma clang
                    fp contract(off)]
           Product: clang
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: C++
          Assignee: unassignedclangbugs at nondot.org
          Reporter: guille at berkeley.edu
                CC: blitzrakete at gmail.com, dgregor at apple.com,
                    erik.pilkington at gmail.com, llvm-bugs at lists.llvm.org,
                    richard-llvm at metafoo.co.uk

Trying to prevent contracting (*,+) into an FMA operation (to guarantee
cross_product(a, a) == 0). 
I add '#pragma clang fp contract(off)' to the start of a block, compiler
accepts the pragma, but still generates an FMA instruction. 

Example at: godbolt.org/z/Cg8rYi

Thanks.

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