[llvm] [ValueTracking] Propagate non-negativity through fptosi (PR #217868)

[Aayush Shrivastava via llvm-commits]

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@@ -5259,7 +5259,7 @@ define float @test_pow_afn_nnan_ninf_f32_known_integral_uitofp(float %x, i32 %y)
 ; PRELINK-NEXT:    [[TMP1:%.*]] = fptosi float [[Y_CAST]] to i32
 ; PRELINK-NEXT:    [[__FABS:%.*]] = call nnan ninf afn float @llvm.fabs.f32(float [[X]])
 ; PRELINK-NEXT:    [[__LOG2:%.*]] = call nnan ninf afn float @llvm.log2.f32(float [[__FABS]])
-; PRELINK-NEXT:    [[POWNI2F:%.*]] = sitofp nnan ninf afn i32 [[TMP1]] to float
+; PRELINK-NEXT:    [[POWNI2F:%.*]] = uitofp nneg i32 [[TMP1]] to float
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iamaayushrivastava wrote:

Thanks for confirming, @dtcxzyw. Fixed `visitSIToFP` to propagate `ninf/nsz` onto the new `uitofp` (the flags that stay meaningful per #198470), while still dropping nnan/afn/etc. as those don't carry real information for a value preserving cast.

https://github.com/llvm/llvm-project/pull/217868