PR rtl-optimization/57281

	PR rtl-optimization/57300
	* config/i386/i386.md (extendsidi2_1 dead reg splitter): Remove.
	(extendsidi2_1 peephole2s): Add instead 2 new peephole2s, that undo
	what the other splitter did if the registers are dead.

	* gcc.dg/pr57300.c: New test.
	* gcc.c-torture/execute/pr57281.c: New test.


git-svn-id: https://gcc.gnu.org/svn/gcc/branches/gcc-4_8-branch@199021 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 40 insertions, 16 deletions

diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 2e450e3d526..455fb63f510 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -3647,22 +3647,8 @@
   "!TARGET_64BIT"
   "#")
 
-;; Extend to memory case when source register does die.
-(define_split
-  [(set (match_operand:DI 0 "memory_operand")
-	(sign_extend:DI (match_operand:SI 1 "register_operand")))
-   (clobber (reg:CC FLAGS_REG))
-   (clobber (match_operand:SI 2 "register_operand"))]
-  "(reload_completed
-    && dead_or_set_p (insn, operands[1])
-    && !reg_mentioned_p (operands[1], operands[0]))"
-  [(set (match_dup 3) (match_dup 1))
-   (parallel [(set (match_dup 1) (ashiftrt:SI (match_dup 1) (const_int 31)))
-	      (clobber (reg:CC FLAGS_REG))])
-   (set (match_dup 4) (match_dup 1))]
-  "split_double_mode (DImode, &operands[0], 1, &operands[3], &operands[4]);")
-
-;; Extend to memory case when source register does not die.
+;; Split the memory case.  If the source register doesn't die, it will stay
+;; this way, if it does die, following peephole2s take care of it.
 (define_split
   [(set (match_operand:DI 0 "memory_operand")
 	(sign_extend:DI (match_operand:SI 1 "register_operand")))
@@ -3691,6 +3677,44 @@
   DONE;
 })
 
+;; Peepholes for the case where the source register does die, after
+;; being split with the above splitter.
+(define_peephole2
+  [(set (match_operand:SI 0 "memory_operand")
+	(match_operand:SI 1 "register_operand"))
+   (set (match_operand:SI 2 "register_operand") (match_dup 1))
+   (parallel [(set (match_dup 2)
+		   (ashiftrt:SI (match_dup 2) (const_int 31)))
+	       (clobber (reg:CC FLAGS_REG))])
+   (set (match_operand:SI 3 "memory_operand") (match_dup 2))]
+  "REGNO (operands[1]) != REGNO (operands[2])
+   && peep2_reg_dead_p (2, operands[1])
+   && peep2_reg_dead_p (4, operands[2])
+   && !reg_mentioned_p (operands[2], operands[3])"
+  [(set (match_dup 0) (match_dup 1))
+   (parallel [(set (match_dup 1) (ashiftrt:SI (match_dup 1) (const_int 31)))
+	      (clobber (reg:CC FLAGS_REG))])
+   (set (match_dup 3) (match_dup 1))])
+
+(define_peephole2
+  [(set (match_operand:SI 0 "memory_operand")
+	(match_operand:SI 1 "register_operand"))
+   (parallel [(set (match_operand:SI 2 "register_operand")
+		   (ashiftrt:SI (match_dup 1) (const_int 31)))
+	       (clobber (reg:CC FLAGS_REG))])
+   (set (match_operand:SI 3 "memory_operand") (match_dup 2))]
+  "/* cltd is shorter than sarl $31, %eax */
+   !optimize_function_for_size_p (cfun)
+   && true_regnum (operands[1]) == AX_REG
+   && true_regnum (operands[2]) == DX_REG
+   && peep2_reg_dead_p (2, operands[1])
+   && peep2_reg_dead_p (3, operands[2])
+   && !reg_mentioned_p (operands[2], operands[3])"
+  [(set (match_dup 0) (match_dup 1))
+   (parallel [(set (match_dup 1) (ashiftrt:SI (match_dup 1) (const_int 31)))
+	      (clobber (reg:CC FLAGS_REG))])
+   (set (match_dup 3) (match_dup 1))])
+
 ;; Extend to register case.  Optimize case where source and destination
 ;; registers match and cases where we can use cltd.
 (define_split