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Re: [PATCH][ARM] Improve use of conditional execution in thumb mode.


And again with the attachment.

On Tue 14 Feb 2012 18:00:57 GMT, Andrew Stubbs wrote:
On Tue 14 Feb 2012 17:35:36 GMT, Richard Earnshaw wrote:
Bernds checked in a patch last year (or maybe even before that) to make
the selection of flags clobbered insns run very late (certainly after
condexec had run), so I'm not sure why you're not seeing this.

Hm, you mentioned some peepholes. Try removing them....

Hmmm, it seems you're right. The machine reorg pass now takes care of this. Well ... that was easy!

Here's a patch to remove the obsolete peepholes. I've confirmed it
works with the testcase.

OK?

Andrew

2012-02-14  Andrew Stubbs  <ams@codesourcery.com>

	gcc/
	* config/arm/thumb2.md: Delete obsolete peepholes.

	gcc/testsuite/
	* gcc.target/arm/thumb-ifcvt.c: New test case.

---
 gcc/config/arm/thumb2.md                   |  107 ----------------------------
 gcc/testsuite/gcc.target/arm/thumb-ifcvt.c |   19 +++++
 2 files changed, 19 insertions(+), 107 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/arm/thumb-ifcvt.c

diff --git a/gcc/config/arm/thumb2.md b/gcc/config/arm/thumb2.md
index 05585da..799a3df 100644
--- a/gcc/config/arm/thumb2.md
+++ b/gcc/config/arm/thumb2.md
@@ -677,26 +677,6 @@
    (set_attr "length" "2")]
 )
 
-;; Similarly for 16-bit shift instructions
-;; There is no 16-bit rotate by immediate instruction.
-(define_peephole2
-  [(set (match_operand:SI   0 "low_register_operand" "")
-	(match_operator:SI  3 "shift_operator"
-	 [(match_operand:SI 1 "low_register_operand" "")
-	  (match_operand:SI 2 "low_reg_or_int_operand" "")]))]
-  "TARGET_THUMB2
-   && peep2_regno_dead_p(0, CC_REGNUM)
-   && ((GET_CODE(operands[3]) != ROTATE && GET_CODE(operands[3]) != ROTATERT)
-       || REG_P(operands[2]))"
-  [(parallel
-    [(set (match_dup 0)
-	  (match_op_dup 3
-	   [(match_dup 1)
-	    (match_dup 2)]))
-     (clobber (reg:CC CC_REGNUM))])]
-  ""
-)
-
 (define_insn "*thumb2_shiftsi3_short"
   [(set (match_operand:SI   0 "low_register_operand" "=l")
 	(match_operator:SI  3 "shift_operator"
@@ -715,20 +695,6 @@
 		      (const_string "alu_shift_reg")))]
 )
 
-;; 16-bit load immediate
-(define_peephole2
-  [(set (match_operand:QHSI 0 "low_register_operand" "")
-	(match_operand:QHSI 1 "const_int_operand" ""))]
-  "TARGET_THUMB2
-   && peep2_regno_dead_p(0, CC_REGNUM)
-   && (unsigned HOST_WIDE_INT) INTVAL(operands[1]) < 256"
-  [(parallel
-    [(set (match_dup 0)
-	  (match_dup 1))
-     (clobber (reg:CC CC_REGNUM))])]
-  ""
-)
-
 (define_insn "*thumb2_mov<mode>_shortim"
   [(set (match_operand:QHSI 0 "low_register_operand" "=l")
 	(match_operand:QHSI 1 "const_int_operand" "I"))
@@ -739,24 +705,6 @@
    (set_attr "length" "2")]
 )
 
-;; 16-bit add/sub immediate
-(define_peephole2
-  [(set (match_operand:SI 0 "low_register_operand" "")
-	(plus:SI (match_operand:SI 1 "low_register_operand" "")
-		 (match_operand:SI 2 "const_int_operand" "")))]
-  "TARGET_THUMB2
-   && peep2_regno_dead_p(0, CC_REGNUM)
-   && ((rtx_equal_p(operands[0], operands[1])
-	&& INTVAL(operands[2]) > -256 && INTVAL(operands[2]) < 256)
-       || (INTVAL(operands[2]) > -8 && INTVAL(operands[2]) < 8))"
-  [(parallel
-    [(set (match_dup 0)
-	  (plus:SI (match_dup 1)
-		   (match_dup 2)))
-     (clobber (reg:CC CC_REGNUM))])]
-  ""
-)
-
 (define_insn "*thumb2_addsi_short"
   [(set (match_operand:SI 0 "low_register_operand" "=l,l")
 	(plus:SI (match_operand:SI 1 "low_register_operand" "l,0")
@@ -868,35 +816,6 @@
    (set_attr "length" "2,4")]
 )
 
-;; 16-bit encodings of "muls" and "mul<c>".  We only use these when
-;; optimizing for size since "muls" is slow on all known
-;; implementations and since "mul<c>" will be generated by
-;; "*arm_mulsi3_v6" anyhow.  The assembler will use a 16-bit encoding
-;; for "mul<c>" whenever possible anyhow.
-(define_peephole2
-  [(set (match_operand:SI 0 "low_register_operand" "")
-        (mult:SI (match_operand:SI 1 "low_register_operand" "")
-                 (match_dup 0)))]
-  "TARGET_THUMB2 && optimize_size && peep2_regno_dead_p (0, CC_REGNUM)"
-  [(parallel
-    [(set (match_dup 0)
-           (mult:SI (match_dup 0) (match_dup 1)))
-     (clobber (reg:CC CC_REGNUM))])]
-  ""
-)
-
-(define_peephole2
-  [(set (match_operand:SI 0 "low_register_operand" "")
-        (mult:SI (match_dup 0)
-	         (match_operand:SI 1 "low_register_operand" "")))]
-  "TARGET_THUMB2 && optimize_size && peep2_regno_dead_p (0, CC_REGNUM)"
-  [(parallel
-    [(set (match_dup 0)
-           (mult:SI (match_dup 0) (match_dup 1)))
-     (clobber (reg:CC CC_REGNUM))])]
-  ""
-)
-
 (define_insn "*thumb2_mulsi_short"
   [(set (match_operand:SI 0 "low_register_operand" "=l")
         (mult:SI (match_operand:SI 1 "low_register_operand" "%0")
@@ -979,19 +898,6 @@
 	    (const_int 8)))]
 )
 
-;; 16-bit complement
-(define_peephole2
-  [(set (match_operand:SI 0 "low_register_operand" "")
-	(not:SI (match_operand:SI 1 "low_register_operand" "")))]
-  "TARGET_THUMB2
-   && peep2_regno_dead_p(0, CC_REGNUM)"
-  [(parallel
-    [(set (match_dup 0)
-	  (not:SI (match_dup 1)))
-     (clobber (reg:CC CC_REGNUM))])]
-  ""
-)
-
 (define_insn "*thumb2_one_cmplsi2_short"
   [(set (match_operand:SI 0 "low_register_operand" "=l")
 	(not:SI (match_operand:SI 1 "low_register_operand" "l")))
@@ -1002,19 +908,6 @@
    (set_attr "length" "2")]
 )
 
-;; 16-bit negate
-(define_peephole2
-  [(set (match_operand:SI 0 "low_register_operand" "")
-	(neg:SI (match_operand:SI 1 "low_register_operand" "")))]
-  "TARGET_THUMB2
-   && peep2_regno_dead_p(0, CC_REGNUM)"
-  [(parallel
-    [(set (match_dup 0)
-	  (neg:SI (match_dup 1)))
-     (clobber (reg:CC CC_REGNUM))])]
-  ""
-)
-
 (define_insn "*thumb2_negsi2_short"
   [(set (match_operand:SI 0 "low_register_operand" "=l")
 	(neg:SI (match_operand:SI 1 "low_register_operand" "l")))
diff --git a/gcc/testsuite/gcc.target/arm/thumb-ifcvt.c b/gcc/testsuite/gcc.target/arm/thumb-ifcvt.c
new file mode 100644
index 0000000..b03bbce
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/thumb-ifcvt.c
@@ -0,0 +1,19 @@
+/* Check that Thumb 16-bit shifts can be if-converted.  */
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_thumb2_ok } */
+/* { dg-options "-O2" } */
+
+int
+foo (int a, int b)
+{
+  if (a != b)
+    {
+      a = a << b;
+      a = a >> 1;
+    }
+
+  return a + b;
+}
+
+/* { dg-final { scan-assembler "lslne" } } */
+/* { dg-final { scan-assembler "asrne" } } */

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