[3/3][RTL ifcvt] PR middle-end/37780: Conditional expression with __builtin_clz(...

[3/3][RTL ifcvt] PR middle-end/37780: Conditional expression with __builtin_clz() should be optimized out

	PR middle-end/37780
	* ifcvt.c (noce_try_ifelse_collapse): New function.
	Declare prototype.
	(noce_process_if_block): Call noce_try_ifelse_collapse.
	* simplify-rtx.c (simplify_cond_clz_ctz): New function.
	(simplify_ternary_operation): Use the above to simplify
	conditional CLZ/CTZ expressions.

	* gcc.c-torture/execute/pr37780.c: New test.
	* gcc.target/aarch64/pr37780_1.c: Likewise.
	* gcc.target/arm/pr37780_1.c: Likewise.

From-SVN: r237141