[llvm] [InstCombine] Remove SPF guard for trunc transforms (PR #117535)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Nikita Popov (nikic)

<details>
<summary>Changes</summary>

This shouldn't be necessary anymore now that SPF patterns are canonicalized to intrinsics.

---
Full diff: https://github.com/llvm/llvm-project/pull/117535.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp (-9) 


``````````diff
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 6c2554ea73b7f8..7221c987b98219 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -786,15 +786,6 @@ Instruction *InstCombinerImpl::visitTrunc(TruncInst &Trunc) {
     }
   }
 
-  // Test if the trunc is the user of a select which is part of a
-  // minimum or maximum operation. If so, don't do any more simplification.
-  // Even simplifying demanded bits can break the canonical form of a
-  // min/max.
-  Value *LHS, *RHS;
-  if (SelectInst *Sel = dyn_cast<SelectInst>(Src))
-    if (matchSelectPattern(Sel, LHS, RHS).Flavor != SPF_UNKNOWN)
-      return nullptr;
-
   // See if we can simplify any instructions used by the input whose sole
   // purpose is to compute bits we don't care about.
   if (SimplifyDemandedInstructionBits(Trunc))

``````````

</details>


https://github.com/llvm/llvm-project/pull/117535