combine.c (apply_distributive_law <SUBREG>): Check TRULY_NOOP_TRUNCATION.

* combine.c (apply_distributive_law <SUBREG>): Check TRULY_NOOP_TRUNCATION. From-SVN: r109261

combine.c (apply_distributive_law <SUBREG>): Check TRULY_NOOP_TRUNCATION.
* combine.c (apply_distributive_law <SUBREG>): Check TRULY_NOOP_TRUNCATION. From-SVN: r109261
f13f406e · Adam Nemet · Adam Nemet · 1146e682 · f13f406e · f13f406e
Commit f13f406e authored Jan 03, 2006 by Adam Nemet Committed by Adam Nemet Jan 03, 2006
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gcc/ChangeLog
+5 -0

gcc/combine.c
+6 -1

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--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
+2006-01-02  Adam Nemet  <anemet@caviumnetworks.com>
+
+	* combine.c (apply_distributive_law <SUBREG>): Check
+	TRULY_NOOP_TRUNCATION.
+
 2006-01-02  Geoffrey Keating  <geoffk@apple.com>

 	* dwarf2out.c (have_switched_text_section): Delete.

--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -7798,7 +7798,12 @@ apply_distributive_law (rtx x)
 	  || (GET_MODE_SIZE (GET_MODE (lhs))
 	      > GET_MODE_SIZE (GET_MODE (SUBREG_REG (lhs))))
 	  || VECTOR_MODE_P (GET_MODE (lhs))
-	  || GET_MODE_SIZE (GET_MODE (SUBREG_REG (lhs))) > UNITS_PER_WORD)
+	  || GET_MODE_SIZE (GET_MODE (SUBREG_REG (lhs))) > UNITS_PER_WORD
+	  /* Result might need to be truncated.  Don't change mode if
+	     explicit truncation is needed.  */
+	  || !TRULY_NOOP_TRUNCATION
+	       (GET_MODE_BITSIZE (GET_MODE (x)),
+		GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (lhs)))))
 	return x;

      tem = simplify_gen_binary (code, GET_MODE (SUBREG_REG (lhs)),