[PATCH] D129958: [IndVars] Eliminate redundant type cast with different sizes

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
Comment at: llvm/lib/Transforms/Utils/SimplifyIndVar.cpp:713
+          Conv = Builder.CreateTrunc(IVOperand, CI->getType(), Name + ".trunc");
+        } else if (Opcode == CastInst::FPToSI) {
+          Conv = Builder.CreateSExt(IVOperand, CI->getType(), Name + ".sext");
----------------
I believe we only need sext if both fptosi and sitofp are used. If one of them is unsigned, then we can use zext. This would match InstCombine logic.

In any case, we should have a test for the uitofp+fptosi combination.


================
Comment at: llvm/test/Transforms/IndVarSimplify/floating-point-small-iv.ll:145
+
+define void @sitofp_fptosi_range_zext() {
+;
----------------
Should be fptoui


================
Comment at: llvm/test/Transforms/IndVarSimplify/floating-point-small-iv.ll:180
+
+define void @sitofp_fptosi_range_zext_postinc() {
+;
----------------
Same here


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D129958/new/

https://reviews.llvm.org/D129958