[PATCH, AArch64] Allow symbol+offset even if not being used for memory access

[Ian Bolton]

Hi,

This patch builds on a previous one that allowed symbol+offset as symbol
references for memory accesses.  It allows us to have symbol+offset even
when no memory access is apparent.

It reduces codesize for cases such as this one:

  int arr[100];

  uint64_t foo (uint64_t a) {
    uint64_t const z = 1234567ll<<32+7;
    uint64_t const y = (uint64_t) &arr[3];
    return y + a + z;
  }

Before the patch, the code looked like this:

    adrp    x2, arr            
    mov     x1, 74217034874880 
    add     x2, x2, :lo12:arr  
    add     x2, x2, 12         
    movk    x1, 2411, lsl 48   
    add     x1, x2, x1         
    add     x0, x1, x0         
    ret                        

Now, it looks like this:
 
    adrp    x1, arr+12
    mov     x2, 74217034874880
    movk    x2, 2411, lsl 48
    add     x1, x1, :lo12:arr+12
    add     x1, x1, x2
    add     x0, x1, x0
    ret

Testing shows no regressions.  OK to commit?


2012-08-31  Ian Bolton  <ian.bol...@arm.com>

        * gcc/config/aarch64/aarch64.md: New pattern.
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index a00d3f0..de9c927 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -2795,7 +2795,7 @@
        (lo_sum:DI (match_operand:DI 1 "register_operand" "r")
                   (match_operand 2 "aarch64_valid_symref" "S")))]
   ""
-  "add\\t%0, %1, :lo12:%2"
+  "add\\t%0, %1, :lo12:%a2"
   [(set_attr "v8type" "alu")
    (set_attr "mode" "DI")]
 
@@ -2890,6 +2890,20 @@
   [(set_attr "length" "0")]
 )
 
+(define_split
+  [(set (match_operand:DI 0 "register_operand" "=r")
+       (const:DI (plus:DI (match_operand:DI 1 "aarch64_valid_symref" "S")
+                          (match_operand:DI 2 "const_int_operand" "i"))))]
+  ""
+  [(set (match_dup 0) (high:DI (const:DI (plus:DI (match_dup 1)
+                                                 (match_dup 2)))))
+   (set (match_dup 0) (lo_sum:DI (match_dup 0)
+                                (const:DI (plus:DI (match_dup 1)
+                                                   (match_dup 2)))))]
+  ""
+)
+
+
 ;; AdvSIMD Stuff
 (include "aarch64-simd.md")