[Mlir-commits] [mlir] [mlir][cf] Canonicalize block args with uniform incoming values (PR #183966)

[Matthias Springer]

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@@ -204,9 +204,81 @@ static LogicalResult simplifyPassThroughBr(BranchOp op,
   return success();
 }
 
+/// If all incoming values for a block argument from all predecessors are the
+/// same SSA value, replace uses of the block argument with that value. This
+/// allows the block argument to be removed by dead code elimination.
+///
+///   %c = arith.constant 0 : i32
+///   cf.br ^bb1(%c : i32)      // pred 1
+///   cf.br ^bb1(%c : i32)      // pred 2
+/// ^bb1(%arg0: i32):
+///   use(%arg0)
+/// ->
+/// ^bb1(%arg0: i32):
+///   use(%c)                   // %arg0 has no uses and can be removed
+///
+static bool simplifyUniformBlockArgs(Block *dest, PatternRewriter &rewriter) {
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matthias-springer wrote:

For consistency, this should return `LogicalResult` like the other functions.

https://github.com/llvm/llvm-project/pull/183966