[AArch64] Allow shrink-wrapping of non-leaf vector PCS functions

With the function ABI stuff, we can now support shrink-wrapping of
non-leaf vector PCS functions.  This is particularly useful if the
vector PCS function calls an ordinary function on an error path,
since we can then keep the extra saves and restores specific to
that path too.

2019-09-30  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/aarch64/aarch64-protos.h (aarch64_use_simple_return_insn_p):
	Delete.
	* config/aarch64/aarch64.c (aarch64_components_for_bb): Check
	whether the block calls a function that clobbers more registers
	than the current function is allowed to.
	(aarch64_use_simple_return_insn_p): Delete.
	* config/aarch64/aarch64.md (simple_return): Remove condition.

gcc/testsuite/
	* gcc.target/aarch64/torture/simd-abi-9.c: New test.

From-SVN: r276340

3 files changed, 21 insertions, 18 deletions

diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
index a870eb7..c9a3423 100644
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -531,7 +531,6 @@ bool aarch64_split_dimode_const_store (rtx, rtx);
 bool aarch64_symbolic_address_p (rtx);
 bool aarch64_uimm12_shift (HOST_WIDE_INT);
 bool aarch64_use_return_insn_p (void);
-bool aarch64_use_simple_return_insn_p (void);
 const char *aarch64_output_casesi (rtx *);
 
 enum aarch64_symbol_type aarch64_classify_symbol (rtx, HOST_WIDE_INT);
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 2d4cd37..3da92a2 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -5976,13 +5976,30 @@ aarch64_components_for_bb (basic_block bb)
   sbitmap components = sbitmap_alloc (LAST_SAVED_REGNUM + 1);
   bitmap_clear (components);
 
+  /* Clobbered registers don't generate values in any meaningful sense,
+     since nothing after the clobber can rely on their value.  And we can't
+     say that partially-clobbered registers are unconditionally killed,
+     because whether they're killed or not depends on the mode of the
+     value they're holding.  Thus partially call-clobbered registers
+     appear in neither the kill set nor the gen set.
+
+     Check manually for any calls that clobber more of a register than the
+     current function can.  */
+  function_abi_aggregator callee_abis;
+  rtx_insn *insn;
+  FOR_BB_INSNS (bb, insn)
+    if (CALL_P (insn))
+      callee_abis.note_callee_abi (insn_callee_abi (insn));
+  HARD_REG_SET extra_caller_saves = callee_abis.caller_save_regs (*crtl->abi);
+
   /* GPRs are used in a bb if they are in the IN, GEN, or KILL sets.  */
   for (unsigned regno = 0; regno <= LAST_SAVED_REGNUM; regno++)
     if ((!call_used_or_fixed_reg_p (regno)
 	|| (simd_function && FP_SIMD_SAVED_REGNUM_P (regno)))
-       && (bitmap_bit_p (in, regno)
-	   || bitmap_bit_p (gen, regno)
-	   || bitmap_bit_p (kill, regno)))
+	&& (TEST_HARD_REG_BIT (extra_caller_saves, regno)
+	    || bitmap_bit_p (in, regno)
+	    || bitmap_bit_p (gen, regno)
+	    || bitmap_bit_p (kill, regno)))
       {
 	unsigned regno2, offset, offset2;
 	bitmap_set_bit (components, regno);
@@ -6648,19 +6665,6 @@ aarch64_use_return_insn_p (void)
   return known_eq (cfun->machine->frame.frame_size, 0);
 }
 
-/* Return false for non-leaf SIMD functions in order to avoid
-   shrink-wrapping them.  Doing this will lose the necessary
-   save/restore of FP registers.  */
-
-bool
-aarch64_use_simple_return_insn_p (void)
-{
-  if (aarch64_simd_decl_p (cfun->decl) && !crtl->is_leaf)
-    return false;
-
-  return true;
-}
-
 /* Generate the epilogue instructions for returning from a function.
    This is almost exactly the reverse of the prolog sequence, except
    that we need to insert barriers to avoid scheduling loads that read
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index edeaa6f..fcba5ac 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -799,7 +799,7 @@
 
 (define_insn "simple_return"
   [(simple_return)]
-  "aarch64_use_simple_return_insn_p ()"
+  ""
   "ret"
   [(set_attr "type" "branch")]
 )