Patchwork [03/18] TCG: remove broken stack allocation for call arguments

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Submitter Blue Swirl
Date May 28, 2011, 10:06 a.m.
Message ID <BANLkTik+Ya=yPoUjJX0QK6bHqxV6jf5CWQ@mail.gmail.com>
Download mbox | patch
Permalink /patch/97776/
State New
Headers show

Comments

Blue Swirl - May 28, 2011, 10:06 a.m.
The code for stack allocation for call arguments is way too simplistic
to actually work on targets with non-trivial stack allocation policies,
e.g. ppc64. We've also already allocated TCG_STATIC_CALL_ARGS_SIZE worth
of stack for calls which should be well more than any helper needs.

Remove broken dynamic stack allocation code and replace it with an assert.
Should dynamic stack allocation ever be needed again, target specific
functions should be added.

Thanks to Richard Henderson for the analysis.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
---
 tcg/tcg.c |    9 +++------
 1 files changed, 3 insertions(+), 6 deletions(-)

     stack_offset = TCG_TARGET_CALL_STACK_OFFSET;
@@ -1971,10 +1972,6 @@ static int tcg_reg_alloc_call(TCGContext *s,
const TCGOpDef *def,
     }

     tcg_out_op(s, opc, &func_arg, &const_func_arg);
-
-    if (allocate_args) {
-        tcg_out_addi(s, TCG_REG_CALL_STACK, STACK_DIR(call_stack_size));
-    }

     /* assign output registers and emit moves if needed */
     for(i = 0; i < nb_oargs; i++) {

Patch

diff --git a/tcg/tcg.c b/tcg/tcg.c
index b31d80d..226f1a1 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1846,13 +1846,14 @@  static int tcg_reg_alloc_call(TCGContext *s,
const TCGOpDef *def,
         nb_regs = nb_params;

     /* assign stack slots first */
-    /* XXX: preallocate call stack */
     call_stack_size = (nb_params - nb_regs) * sizeof(tcg_target_long);
     call_stack_size = (call_stack_size + TCG_TARGET_STACK_ALIGN - 1) &
         ~(TCG_TARGET_STACK_ALIGN - 1);
     allocate_args = (call_stack_size > TCG_STATIC_CALL_ARGS_SIZE);
     if (allocate_args) {
-        tcg_out_addi(s, TCG_REG_CALL_STACK, -STACK_DIR(call_stack_size));
+        /* XXX: if more than TCG_STATIC_CALL_ARGS_SIZE is needed,
+           preallocate call stack */
+        tcg_abort();
     }