sim: sh: rework carry checks to not rely on integer overflows

In <=gcc-7 versions, -fstrict-overflow is enabled by default, and that
triggers warnings in this code that relies on integer overflows to test
for carries.  Change the logic to test against the limit directly.

diff --git a/sim/sh/gencode.c b/sim/sh/gencode.c
index 80eecfdf1d3687e192c0576a97ece63413a60eb5..5eb7caf258936972082a6c9c84e99b3fe47a3141 100644 (file)
--- a/sim/sh/gencode.c
+++ b/sim/sh/gencode.c
@@ -2266,7 +2266,7 @@ op ppi_tab[] =
     "int Sx_grd = GET_DSP_GRD (x);",
     "",
     "res = Sx - 0x10000;",
-    "carry = res > Sx;",
+    "carry = Sx < (INT_MIN + 0x10000);",
     "res_grd = Sx_grd - carry;",
     "COMPUTE_OVERFLOW;",
     "ADD_SUB_GE;",
@@ -2277,7 +2277,7 @@ op ppi_tab[] =
     "int Sx_grd = GET_DSP_GRD (x);",
     "",
     "res = Sx + 0x10000;",
-    "carry = res < Sx;",
+    "carry = Sx > (INT_MAX - 0x10000);",
     "res_grd = Sx_grd + carry;",
     "COMPUTE_OVERFLOW;",
     "ADD_SUB_GE;",
@@ -2288,7 +2288,7 @@ op ppi_tab[] =
     "int Sy_grd = SIGN32 (Sy);",
     "",
     "res = Sy - 0x10000;",
-    "carry = res > Sy;",
+    "carry = Sy < (INT_MIN + 0x10000);",
     "res_grd = Sy_grd - carry;",
     "COMPUTE_OVERFLOW;",
     "ADD_SUB_GE;",
@@ -2299,7 +2299,7 @@ op ppi_tab[] =
     "int Sy_grd = SIGN32 (Sy);",
     "",
     "res = Sy + 0x10000;",
-    "carry = res < Sy;",
+    "carry = Sy > (INT_MAX - 0x10000);",
     "res_grd = Sy_grd + carry;",
     "COMPUTE_OVERFLOW;",
     "ADD_SUB_GE;",