Merge pull request #7946 from koachan/sparc64-framefixes

SPARCv9: Handle various stack frame related quirks.

1 files changed, 17 insertions, 3 deletions

diff --git a/lib/std/debug.zig b/lib/std/debug.zig
index f32c1a6156..74fb95ffa8 100644
--- a/lib/std/debug.zig
+++ b/lib/std/debug.zig
@@ -360,14 +360,24 @@ pub const StackIterator = struct {
         };
     }
 
-    // Negative offset of the saved BP wrt the frame pointer.
+    // Offset of the saved BP wrt the frame pointer.
     const fp_offset = if (builtin.arch.isRISCV())
         // On RISC-V the frame pointer points to the top of the saved register
         // area, on pretty much every other architecture it points to the stack
         // slot where the previous frame pointer is saved.
         2 * @sizeOf(usize)
+    else if (builtin.arch.isSPARC())
+        // On SPARC the previous frame pointer is stored at 14 slots past %fp+BIAS.
+        14 * @sizeOf(usize)
     else
         0;
+
+    const fp_bias = if (builtin.arch.isSPARC())
+        // On SPARC frame pointers are biased by a constant.
+        2047
+    else
+        0;
+
     // Positive offset of the saved PC wrt the frame pointer.
     const pc_offset = if (builtin.arch == .powerpc64le)
         2 * @sizeOf(usize)
@@ -388,13 +398,17 @@ pub const StackIterator = struct {
     }
 
     fn next_internal(self: *StackIterator) ?usize {
-        const fp = math.sub(usize, self.fp, fp_offset) catch return null;
+        const fp = if (builtin.arch.isSPARC())
+            // On SPARC the offset is positive. (!)
+            math.add(usize, self.fp, fp_offset) catch return null
+        else
+            math.sub(usize, self.fp, fp_offset) catch return null;
 
         // Sanity check.
         if (fp == 0 or !mem.isAligned(fp, @alignOf(usize)))
             return null;
 
-        const new_fp = @intToPtr(*const usize, fp).*;
+        const new_fp = math.add(usize, @intToPtr(*const usize, fp).*, fp_bias) catch return null;
 
         // Sanity check: the stack grows down thus all the parent frames must be
         // be at addresses that are greater (or equal) than the previous one.