re PR target/40603 (unnecessary conversion from unsigned byte load to signed byte load)

	PR target/40603
	* config/arm/arm.md (cbranchqi4): New pattern.
	* config/arm/predicates.md (const0_operand,
	cbranchqi4_comparison_operator): New predicates.

	PR target/40603
	* gcc.target/arm/thumb-cbranchqi.c: New test.

From-SVN: r158407

5 files changed, 66 insertions, 10 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index bca40b7..38952fc 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,9 +1,16 @@
+2010-04-16  Bernd Schmidt  <bernds@codesourcery.com>
+
+	PR target/40603
+	* config/arm/arm.md (cbranchqi4): New pattern.
+	* config/arm/predicates.md (const0_operand,
+	cbranchqi4_comparison_operator): New predicates.
+
 2010-04-16  Richard Guenther  <rguenther@suse.de>
 
 	* gimple-pretty-print.c (dump_gimple_phi): Dump alias info.
 	(dump_gimple_stmt): Likewise.
 
-2010-04-16  Bernd Schmidt  <bernd.schmidt@codesourcery.com>
+2010-04-16  Bernd Schmidt  <bernds@codesourcery.com>
 
 	* recog.h (struct recog_data): New field is_operator.
 	(struct insn_operand_data): New field is_operator.
@@ -178,7 +185,7 @@
 	div_and_round_double): Move prototypes ...
 	* double-int.h: ... here.
 
-2010-04-15  Bernd Schmidt  <bernd.schmidt@codesourcery.com>
+2010-04-15  Bernd Schmidt  <bernds@codesourcery.com>
 
 	PR target/43742
 	* config/sh/sh.md (doloop_end_split, dect): Undo previous patch.  Use
@@ -206,7 +213,7 @@
 	comment.
 	* expmed.c (mask_rtx, lshift_value): (Ditto.).
 
-2010-04-14  Bernd Schmidt  <bernd.schmidt@codesourcery.com>
+2010-04-14  Bernd Schmidt  <bernds@codesourcery.com>
 	
 	PR target/21803
 	* ifcvt.c (cond_exec_process_if_block): Look for identical sequences
@@ -790,7 +797,7 @@
 	(arm_output_addr_const_extra): Output expression for new pattern.
 	* config/arm/arm.md (UNSPEC_SYMBOL_OFFSET): New unspec symbol.
 
-2010-04-10  Bernd Schmidt  <bernd.schmidt@codesourcery.com>
+2010-04-10  Bernd Schmidt  <bernds@codesourcery.com>
 
 	* ira-costs.c (record_reg_classes): Ignore alternatives that are
 	not enabled.
@@ -820,7 +827,7 @@
 	* ipa-prop.c (ipa_print_node_jump_functions): Likewise.
 
 2010-04-09  Eric Botcazou  <ebotcazou@adacore.com>
-	    Bernd Schmidt  <bernd.schmidt@codesourcery.com>
+	    Bernd Schmidt  <bernds@codesourcery.com>
 
 	* loop-invariant.c (replace_uses): New static function.
 	(move_invariant_reg): Use it to ensure we can replace the uses.
@@ -2354,7 +2361,7 @@
 	* c-decl.c (grokparms): Set arg_types to NULL_TREE if there was
 	an error.
 
-2010-03-19  Bernd Schmidt  <bernd.schmidt@codesourcery.com>
+2010-03-19  Bernd Schmidt  <bernds@codesourcery.com>
 
 	PR rtl-optimization/42258
 	* ira-lives.c (check_and_make_def_conflict): Ignore conflict for a
diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 4604e13..fb9c024 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -6668,6 +6668,30 @@
     operands[2] = force_reg (SImode, operands[2]);
   ")
 
+;; A pattern to recognize a special situation and optimize for it.
+;; On the thumb, zero-extension from memory is preferrable to sign-extension
+;; due to the available addressing modes.  Hence, convert a signed comparison
+;; with zero into an unsigned comparison with 127 if possible.
+(define_expand "cbranchqi4"
+  [(set (pc) (if_then_else
+	      (match_operator 0 "lt_ge_comparison_operator"
+	       [(match_operand:QI 1 "memory_operand" "")
+	        (match_operand:QI 2 "const0_operand" "")])
+	      (label_ref (match_operand 3 "" ""))
+	      (pc)))]
+  "TARGET_THUMB1"
+{
+  rtx xops[3];
+  xops[1] = gen_reg_rtx (SImode);
+  emit_insn (gen_zero_extendqisi2 (xops[1], operands[1]));
+  xops[2] = GEN_INT (127);
+  xops[0] = gen_rtx_fmt_ee (GET_CODE (operands[0]) == GE ? LEU : GTU,
+			    VOIDmode, xops[1], xops[2]);
+  xops[3] = operands[3];
+  emit_insn (gen_cbranchsi4 (xops[0], xops[1], xops[2], xops[3]));
+  DONE;
+})
+
 (define_expand "cbranchsf4"
   [(set (pc) (if_then_else
 	      (match_operator 0 "arm_comparison_operator"
diff --git a/gcc/config/arm/predicates.md b/gcc/config/arm/predicates.md
index d351f44..a60da9a 100644
--- a/gcc/config/arm/predicates.md
+++ b/gcc/config/arm/predicates.md
@@ -94,6 +94,10 @@
   (and (match_code "const_int")
        (match_test "const_ok_for_arm (~INTVAL (op))")))
 
+(define_predicate "const0_operand"
+  (and (match_code "const_int")
+       (match_test "INTVAL (op) == 0")))
+
 ;; Something valid on the RHS of an ARM data-processing instruction
 (define_predicate "arm_rhs_operand"
   (ior (match_operand 0 "s_register_operand")
@@ -203,6 +207,9 @@
 			 && (TARGET_FPA || TARGET_VFP)")
             (match_code "unordered,ordered,unlt,unle,unge,ungt"))))
 
+(define_special_predicate "lt_ge_comparison_operator"
+  (match_code "lt,ge"))
+
 (define_special_predicate "minmax_operator"
   (and (match_code "smin,smax,umin,umax")
        (match_test "mode == GET_MODE (op)")))
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3f0fe2b..450aa4f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,7 +1,10 @@
-2010-04-16  Bernd Schmidt  <bernd.schmidt@codesourcery.com>
+2010-04-16  Bernd Schmidt  <bernds@codesourcery.com>
 
 	PR target/41514
-	gcc.target/arm/thumb-comparisons.c: New test.
+	* gcc.target/arm/thumb-comparisons.c: New test.
+
+	PR target/40603
+	* gcc.target/arm/thumb-cbranchqi.c: New test.
 
 2010-04-16  Christian Bruel  <christian.bruel@st.com>
 
@@ -30,7 +33,7 @@
 	* gcc.dg/torture/ipa-pta-2.c: Likewise.
 	* gcc.dg/torture/ipa-pta-1.c: Adjust.
 
-2010-04-14  Bernd Schmidt  <bernd.schmidt@codesourcery.com>
+2010-04-14  Bernd Schmidt  <bernds@codesourcery.com>
 
 	PR target/21803
 	* gcc.target/arm/pr42496.c: New test.
@@ -1217,7 +1220,7 @@
 	* gcc.dg/pr43211.c: New test.
 	* gcc.dg/pr18809-1.c: Don't expect an error when calling foo.
 
-2010-03-19  Bernd Schmidt  <bernd.schmidt@codesourcery.com>
+2010-03-19  Bernd Schmidt  <bernds@codesourcery.com>
 
 	PR rtl-optimization/42258
 	* gcc.target/arm/thumb1-mul-moves.c: New test.
diff --git a/gcc/testsuite/gcc.target/arm/thumb-cbranchqi.c b/gcc/testsuite/gcc.target/arm/thumb-cbranchqi.c
new file mode 100644
index 0000000..ad28e7f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/thumb-cbranchqi.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-mthumb -Os" }  */
+/* { dg-require-effective-target arm_thumb1_ok } */
+
+int ldrb(unsigned char* p)
+{
+  if (p[8] <= 0x7F)
+    return 2;
+  else
+    return 5;
+}
+
+
+/* { dg-final { scan-assembler "127" } } */
+/* { dg-final { scan-assembler "bhi" } } */