[PATCH] D154496: InstCombine: Fold ldexp(ldexp(x, a), b) -> ldexp(x, a + b)

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp:2381-2383
+    // It's also safe to fold if we know both exponents have the same sign since
+    // it would just double down on the overflow/underflow which would occur
+    // anyway.
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foad wrote:
> Additionally it would be safe if both exponents are known to be <= 0, but I guess we don't have a helper function for that.
Right we totally lack FP range tracking


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https://reviews.llvm.org/D154496