https://llvm.org/bugs/show_bug.cgi?id=27794
Bug ID: 27794 Summary: missing optimization of multiply overflow check Product: new-bugs Version: trunk Hardware: PC OS: All Status: NEW Severity: normal Priority: P Component: new bugs Assignee: unassignedb...@nondot.org Reporter: reg...@cs.utah.edu CC: llvm-bugs@lists.llvm.org Classification: Unclassified This is a portable, UB-free idiom for seeing if a multiply is going to overflow: int f(unsigned a, unsigned b) { return a > (UINT_MAX / b); } we should turn this into a multiply with condition code and then also CSE it with the multiply itself which will surely be nearby. Request for this optimization comes from Rich Felker, author of Musl libc: http://wiki.musl-libc.org/wiki/Projects_using_musl This should be done in CodeGenPrepare, Sanjoy Das says. -- You are receiving this mail because: You are on the CC list for the bug.
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