From e045b85836091f2461263a3c3f4f1972b3753f9d Mon Sep 17 00:00:00 2001
From: Jozef Lawrynowicz <jozef.l@mittosystems.com>
Date: Sun, 15 Nov 2020 21:03:10 +0000
Subject: [PATCH] MSP430: Add mul{hi,si} and {u,}mulsidi3 expanders

GCC generates better code when multiplication operations, which require
library functions to perform, are caught in early in RTL, rather than
leaving the operation to be mapped to a library function later on.

When there is hardware multiply support, it is more efficient to perform
widening multiplication using the hardware multiplier instead of letting
GCC widen the arguments before calling the multiplication routine in the
wider mode.

gcc/ChangeLog:

	* config/msp430/msp430.md (mulhi3): New.
	(mulsi3): New.
	(mulsidi3): Rename to *mulsidi3_inline.
	(umulsidi3): Rename to *umulsidi3_inline.
	(mulsidi3): New define_expand.
	(umulsidi3): New define_expand.
---
 gcc/config/msp430/msp430.md | 61 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 56 insertions(+), 5 deletions(-)

diff --git a/gcc/config/msp430/msp430.md b/gcc/config/msp430/msp430.md
index 65e9517..1ec219c 100644
--- a/gcc/config/msp430/msp430.md
+++ b/gcc/config/msp430/msp430.md
@@ -1724,6 +1724,28 @@
   [(set_attr "length" "2")]
 )
 
+(define_expand "mulhi3"
+  [(set (match_operand:HI			   0 "register_operand" "=r")
+	(mult:HI (match_operand:HI 1 "register_operand" "%0")
+		 (match_operand:HI 2 "register_operand" "r")))]
+  "msp430_has_hwmult ()"
+  {
+    msp430_expand_helper (operands, "__mspabi_mpyi", false);
+    DONE;
+  }
+)
+
+(define_expand "mulsi3"
+  [(set (match_operand:SI			   0 "register_operand" "=r")
+	(mult:SI (match_operand:SI 1 "register_operand" "%0")
+		 (match_operand:SI 2 "register_operand" "r")))]
+  "msp430_has_hwmult ()"
+  {
+    msp430_expand_helper (operands, "__mspabi_mpyl", false);
+    DONE;
+  }
+)
+
 ; libgcc helper functions for widening multiplication aren't currently
 ; generated by gcc, so we can't catch them later and map them to the mspabi
 ; functions.
@@ -1733,9 +1755,7 @@
 ; If we don't have hardware multiply support, it will generally be slower and
 ; result in larger code to call the mspabi library function to perform the
 ; widening multiplication than just leaving GCC to widen the arguments itself.
-;
-; We don't use library functions for SImode->DImode widening since its always
-; larger and slower than letting GCC widen the arguments inline.
+
 (define_expand "mulhisi3"
   [(set (match_operand:SI			   0 "register_operand" "=r")
 	(mult:SI (sign_extend:SI (match_operand:HI 1 "register_operand" "%0"))
@@ -1766,6 +1786,37 @@
   }
 )
 
+(define_expand "mulsidi3"
+  [(set (match_operand:DI			   0 "register_operand" "=r")
+	(mult:DI (sign_extend:DI (match_operand:SI 1 "register_operand" "%0"))
+		 (sign_extend:DI (match_operand:SI 2 "register_operand" "r"))))]
+  "msp430_has_hwmult ()"
+  {
+    /* Leave the other case for the inline insn.  */
+    if (!(optimize > 2 && msp430_has_hwmult ()))
+    {
+      msp430_expand_helper (operands, "__mspabi_mpysll", false);
+      DONE;
+    }
+  }
+)
+
+(define_expand "umulsidi3"
+  [(set (match_operand:DI			   0 "register_operand" "=r")
+	(mult:DI (zero_extend:DI (match_operand:SI 1 "register_operand" "%0"))
+		 (zero_extend:DI (match_operand:SI 2 "register_operand" "r"))))]
+  "msp430_has_hwmult ()"
+  {
+    /* Leave the other case for the inline insn.  */
+    if (!(optimize > 2 && msp430_has_hwmult ()))
+    {
+      msp430_expand_helper (operands, "__mspabi_mpyull", false);
+      DONE;
+    }
+  }
+)
+
+
 (define_insn "*mulhisi3_inline"
   [(set (match_operand:SI                          0 "register_operand" "=r")
 	(mult:SI (sign_extend:SI (match_operand:HI 1 "register_operand" "%0"))
@@ -1794,7 +1845,7 @@
   [(set_attr "length" "24")]
 )
 
-(define_insn "mulsidi3"
+(define_insn "*mulsidi3_inline"
   [(set (match_operand:DI                          0 "register_operand" "=r")
 	(mult:DI (sign_extend:DI (match_operand:SI 1 "register_operand" "%0"))
 		 (sign_extend:DI (match_operand:SI 2 "register_operand" "r"))))]
@@ -1808,7 +1859,7 @@
   [(set_attr "length" "40")]
 )
 
-(define_insn "umulsidi3"
+(define_insn "*umulsidi3_inline"
   [(set (match_operand:DI                          0 "register_operand" "=r")
 	(mult:DI (zero_extend:DI (match_operand:SI 1 "register_operand" "%0"))
 		 (zero_extend:DI (match_operand:SI 2 "register_operand" "r"))))]
-- 
2.7.4