[PATCH] rs6000: Fix stack clash for big residuals (PR85287)

[Segher Boessenkool]

The stack clash protection code had a logic error in how it decided
whether to put the final update size in a register, or to emit it
directly in an insn.  This fixes it.  It also tidies some surrounding
code.


Segher


2018-04-10  Segher Boessenkool  <seg...@kernel.crashing.org>

        * gcc/config/rs6000/rs6000.md (allocate_stack): Put the residual size
        for stack clash protection in a register whenever we need it to be in
        a register.

---
 gcc/config/rs6000/rs6000.md | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 62b4aa7..25ac0b8 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -9795,14 +9795,12 @@ (define_expand "allocate_stack"
       /* Now handle residuals.  We just have to set operands[1] correctly
         and let the rest of the expander run.  */
       operands[1] = residual;
-      if (!CONST_INT_P (residual))
-       operands[1] = force_reg (Pmode, operands[1]);
     }
 
-  if (GET_CODE (operands[1]) != CONST_INT
-      || INTVAL (operands[1]) < -32767
-      || INTVAL (operands[1]) > 32768)
+  if (!(CONST_INT_P (operands[1])
+       && IN_RANGE (INTVAL (operands[1]), -32767, 32768)))
     {
+      operands[1] = force_reg (Pmode, operands[1]);
       neg_op0 = gen_reg_rtx (Pmode);
       if (TARGET_32BIT)
        emit_insn (gen_negsi2 (neg_op0, operands[1]));
@@ -9810,7 +9808,7 @@ (define_expand "allocate_stack"
        emit_insn (gen_negdi2 (neg_op0, operands[1]));
     }
   else
-    neg_op0 = GEN_INT (- INTVAL (operands[1]));
+    neg_op0 = GEN_INT (-INTVAL (operands[1]));
 
   insn = emit_insn ((* ((TARGET_32BIT) ? gen_movsi_update_stack
                                       : gen_movdi_di_update_stack))
-- 
1.8.3.1