From: Vladimir N. Makarov <vmakarov@redhat.com>
Date: Fri, 2 Dec 2022 13:18:04 +0000 (-0500)
Subject: LRA: Check hard reg availability of pseudo and its subreg for pseudo reload
X-Git-Tag: basepoints/gcc-14~2741
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=70596a0fb2a2ec072e1e97e37616e05041dfa4e5;p=thirdparty%2Fgcc.git

LRA: Check hard reg availability of pseudo and its subreg for pseudo reload

Do not reload subreg pseudo if there are hard regs for subreg mode
but there are no hard regs for pseudo mode.

        PR target/106462

gcc/ChangeLog:

	* lra-constraints.cc (curr_insn_transform): Check available hard
	regs for pseudo and its subreg to decide what to reload.

gcc/testsuite/ChangeLog:

	* gcc.target/mips/pr106462.c: New test.
---

diff --git a/gcc/lra-constraints.cc b/gcc/lra-constraints.cc
index d92ab76908c8..02b5ab4a3169 100644
--- a/gcc/lra-constraints.cc
+++ b/gcc/lra-constraints.cc
@@ -4582,7 +4582,18 @@ curr_insn_transform (bool check_only_p)
 		      || (partial_subreg_p (mode, GET_MODE (reg))
 			  && known_le (GET_MODE_SIZE (GET_MODE (reg)),
 				       UNITS_PER_WORD)
-			  && WORD_REGISTER_OPERATIONS)))
+			  && WORD_REGISTER_OPERATIONS))
+		  /* Avoid the situation when there are no available hard regs
+		     for the pseudo mode but there are ones for the subreg
+		     mode: */
+		  && !(goal_alt[i] != NO_REGS
+		       && REGNO (reg) >= FIRST_PSEUDO_REGISTER
+		       && (prohibited_class_reg_set_mode_p
+			   (goal_alt[i], reg_class_contents[goal_alt[i]],
+			    GET_MODE (reg)))
+		       && !(prohibited_class_reg_set_mode_p
+			    (goal_alt[i], reg_class_contents[goal_alt[i]],
+			     mode))))
 		{
 		  /* An OP_INOUT is required when reloading a subreg of a
 		     mode wider than a word to ensure that data beyond the
diff --git a/gcc/testsuite/gcc.target/mips/pr106462.c b/gcc/testsuite/gcc.target/mips/pr106462.c
new file mode 100644
index 000000000000..c9105409524d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/pr106462.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-mabi=64 -msingle-float" } */
+
+extern void bar (float x, short y);
+
+void foo (int argc)
+{
+    short c = argc * 2;
+    float a = (float)(short)c, b = 9.5;
+
+    bar (b/a, c);
+}