[AArch64] Tighten move constraints for symbolic operands

The movsi and movdi constraints allowed the source to be any
absolute symbolic expression ("S").  That's OK for operands that
have already been vetted by the aarch64_mov_operand predicate but
causes problems if the register allocator substitutes an equivalence
(the usual "the constraints can't accept more than the predicates"
restriction).

Although all other uses of "S" in the backend are redundant and could
in principle be removed, "S" itself is a publicly-documented constraint
and so we'd have to keep its definition.  This patch therefore adds a
new "Usa" constraint for legitimate absolute address operands.

2017-05-08  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/aarch64/constraints.md (Usa): New constraint.
	* config/aarch64/aarch64.md (*movsi_aarch64, *movdi_aarch64): Use it.

From-SVN: r247746

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fdc151110520f52e4e6ada0573f09b9de2888f76..58693c5a4760b9c1a3236f4d9f5de31ba667c86d 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-05-08  Richard Sandiford  <richard.sandiford@arm.com>
+
+       * config/aarch64/constraints.md (Usa): New constraint.
+       * config/aarch64/aarch64.md (*movsi_aarch64, *movdi_aarch64): Use it.
+
 2017-05-08  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
        * config.gcc (arm*-*-*): Set TM_MULTILIB_CONFIG from

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index c522e87ebdef4b8d6a392f7bfde1d6bf8251b6d9..7cc32dd037c8f41a2f5631139121f51cd56f2d99 100644 (file)
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -1031,7 +1031,7 @@
 
 (define_insn_and_split "*movsi_aarch64"
   [(set (match_operand:SI 0 "nonimmediate_operand" "=r,k,r,r,r,r,*w,m,  m,r,r  ,*w,r,*w")
-       (match_operand:SI 1 "aarch64_mov_operand"  " r,r,k,M,n,m, m,rZ,*w,S,Ush,rZ,w,*w"))]
+       (match_operand:SI 1 "aarch64_mov_operand"  " r,r,k,M,n,m, m,rZ,*w,Usa,Ush,rZ,w,*w"))]
   "(register_operand (operands[0], SImode)
     || aarch64_reg_or_zero (operands[1], SImode))"
   "@
@@ -1063,7 +1063,7 @@
 
 (define_insn_and_split "*movdi_aarch64"
   [(set (match_operand:DI 0 "nonimmediate_operand" "=r,k,r,r,r,r,*w,m,  m,r,r,  *w,r,*w,w")
-       (match_operand:DI 1 "aarch64_mov_operand"  " r,r,k,N,n,m, m,rZ,*w,S,Ush,rZ,w,*w,Dd"))]
+       (match_operand:DI 1 "aarch64_mov_operand"  " r,r,k,N,n,m, m,rZ,*w,Usa,Ush,rZ,w,*w,Dd"))]
   "(register_operand (operands[0], DImode)
     || aarch64_reg_or_zero (operands[1], DImode))"
   "@

diff --git a/gcc/config/aarch64/constraints.md b/gcc/config/aarch64/constraints.md
index b8293376fde7e03c4cfc2a6ad6268201f487eb92..b43f08b7bbd1f31d9ff3842cebaccd4e953ab9dc 100644 (file)
--- a/gcc/config/aarch64/constraints.md
+++ b/gcc/config/aarch64/constraints.md
@@ -98,6 +98,14 @@
   (and (match_code "high")
        (match_test "aarch64_valid_symref (XEXP (op, 0), GET_MODE (XEXP (op, 0)))")))
 
+(define_constraint "Usa"
+  "@internal
+   A constraint that matches an absolute symbolic address that can be
+   loaded by a single ADR."
+  (and (match_code "const,symbol_ref,label_ref")
+       (match_test "aarch64_symbolic_address_p (op)")
+       (match_test "aarch64_mov_operand_p (op, GET_MODE (op))")))
+
 (define_constraint "Uss"
   "@internal
   A constraint that matches an immediate shift constant in SImode."