[PATCH 3/5] LoongArch: Take the advantage of -mdiv32 if it's enabled

[Xi Ruoyao <xry111@xry111.site>]

With -mdiv32, we can assume div.w[u] and mod.w[u] works on low 32 bits
of a 64-bit GPR even if it's not sign-extended.

gcc/ChangeLog:

	* config/loongarch/loongarch.md (DIV): New mode iterator.
	(<optab:ANY_DIV><mode:GPR>3): Don't expand if TARGET_DIV32.
	(<optab:ANY_DIV>di3_fake): Disable if TARGET_DIV32.
	(*<optab:ANY_DIV><mode:GPR>3): Allow SImode if TARGET_DIV32.
	(<optab:ANY_DIV>si3_extended): New insn if TARGET_DIV32.

gcc/testsuite/ChangeLog:

	* gcc.target/loongarch/div-div32.c: New test.
	* gcc.target/loongarch/div-no-div32.c: New test.
---
 gcc/config/loongarch/loongarch.md             | 31 ++++++++++++++++---
 .../gcc.target/loongarch/div-div32.c          | 31 +++++++++++++++++++
 .../gcc.target/loongarch/div-no-div32.c       | 11 +++++++
 3 files changed, 68 insertions(+), 5 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/loongarch/div-div32.c
 create mode 100644 gcc/testsuite/gcc.target/loongarch/div-no-div32.c

diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md
index 22814a3679c..a97e5ee094a 100644
--- a/gcc/config/loongarch/loongarch.md
+++ b/gcc/config/loongarch/loongarch.md
@@ -408,6 +408,10 @@ (define_mode_iterator LD_AT_LEAST_32_BIT [GPR ANYF])
 ;; st.w.
 (define_mode_iterator ST_ANY [QHWD ANYF])
 
+;; A mode for anything legal as a input of a div or mod instruction.
+(define_mode_iterator DIV [(DI "TARGET_64BIT")
+			   (SI "!TARGET_64BIT || TARGET_DIV32")])
+
 ;; In GPR templates, a string like "mul.<d>" will expand to "mul.w" in the
 ;; 32-bit version and "mul.d" in the 64-bit version.
 (define_mode_attr d [(SI "w") (DI "d")])
@@ -914,7 +918,7 @@ (define_expand "<optab><mode>3"
 		     (match_operand:GPR 2 "register_operand")))]
   ""
 {
- if (GET_MODE (operands[0]) == SImode && TARGET_64BIT)
+ if (GET_MODE (operands[0]) == SImode && TARGET_64BIT && !TARGET_DIV32)
   {
     rtx reg1 = gen_reg_rtx (DImode);
     rtx reg2 = gen_reg_rtx (DImode);
@@ -934,9 +938,9 @@ (define_expand "<optab><mode>3"
 })
 
 (define_insn "*<optab><mode>3"
-  [(set (match_operand:X 0 "register_operand" "=r,&r,&r")
-	(any_div:X (match_operand:X 1 "register_operand" "r,r,0")
-		   (match_operand:X 2 "register_operand" "r,r,r")))]
+  [(set (match_operand:DIV 0 "register_operand" "=r,&r,&r")
+	(any_div:DIV (match_operand:DIV 1 "register_operand" "r,r,0")
+		     (match_operand:DIV 2 "register_operand" "r,r,r")))]
   ""
 {
   return loongarch_output_division ("<insn>.<d><u>\t%0,%1,%2", operands);
@@ -949,6 +953,23 @@ (define_insn "*<optab><mode>3"
 	(const_string "yes")
 	(const_string "no")))])
 
+(define_insn "<optab>si3_extended"
+  [(set (match_operand:DI 0 "register_operand" "=r,&r,&r")
+	(sign_extend
+	  (any_div:SI (match_operand:SI 1 "register_operand" "r,r,0")
+		      (match_operand:SI 2 "register_operand" "r,r,r"))))]
+  "TARGET_64BIT && TARGET_DIV32"
+{
+  return loongarch_output_division ("<insn>.w<u>\t%0,%1,%2", operands);
+}
+  [(set_attr "type" "idiv")
+   (set_attr "mode" "SI")
+   (set (attr "enabled")
+      (if_then_else
+	(match_test "!!which_alternative == loongarch_check_zero_div_p()")
+	(const_string "yes")
+	(const_string "no")))])
+
 (define_insn "<optab>di3_fake"
   [(set (match_operand:DI 0 "register_operand" "=r,&r,&r")
 	(sign_extend:DI
@@ -957,7 +978,7 @@ (define_insn "<optab>di3_fake"
 	     (any_div:DI (match_operand:DI 1 "register_operand" "r,r,0")
 			 (match_operand:DI 2 "register_operand" "r,r,r")) 0)]
 	  UNSPEC_FAKE_ANY_DIV)))]
-  "TARGET_64BIT"
+  "TARGET_64BIT && !TARGET_DIV32"
 {
   return loongarch_output_division ("<insn>.w<u>\t%0,%1,%2", operands);
 }
diff --git a/gcc/testsuite/gcc.target/loongarch/div-div32.c b/gcc/testsuite/gcc.target/loongarch/div-div32.c
new file mode 100644
index 00000000000..8b1f686eca2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/div-div32.c
@@ -0,0 +1,31 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=loongarch64 -mabi=lp64d -mdiv32" } */
+/* { dg-final { scan-assembler "div\.w" } } */
+/* { dg-final { scan-assembler "div\.wu" } } */
+/* { dg-final { scan-assembler "mod\.w" } } */
+/* { dg-final { scan-assembler "mod\.wu" } } */
+/* { dg-final { scan-assembler-not "slli\.w.*,0" } } */
+
+int
+divw (long a, long b)
+{
+  return (int)a / (int)b;
+}
+
+unsigned int
+divwu (long a, long b)
+{
+  return (unsigned int)a / (unsigned int)b;
+}
+
+int
+modw (long a, long b)
+{
+  return (int)a % (int)b;
+}
+
+unsigned int
+modwu (long a, long b)
+{
+  return (unsigned int)a % (unsigned int)b;
+}
diff --git a/gcc/testsuite/gcc.target/loongarch/div-no-div32.c b/gcc/testsuite/gcc.target/loongarch/div-no-div32.c
new file mode 100644
index 00000000000..f0f697ba589
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/div-no-div32.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=loongarch64 -mabi=lp64d" } */
+/* { dg-final { scan-assembler "div\.w" } } */
+/* { dg-final { scan-assembler "div\.wu" } } */
+/* { dg-final { scan-assembler "mod\.w" } } */
+/* { dg-final { scan-assembler "mod\.wu" } } */
+
+/* -mno-div32 should be implied by -march=loongarch64.  */
+/* { dg-final { scan-assembler-times "slli\.w\[^\n\]*0" 8 } } */
+
+#include "div-div32.c"
-- 
2.42.1