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std.debug.StackIterator: account for SPARC %fp quirk

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On SPARC, previous %fp is saved with a 14 slots offset from current %fp+bias.
Also account for the bias constant at the new_fp calculation.
This commit is contained in:
Koakuma 2021-02-04 20:51:41 +07:00
parent 2d447b57cc
commit 1eb2e48014
1 changed files with 11 additions and 1 deletions
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12
lib/std/debug.zig
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@ -366,8 +366,18 @@ pub const StackIterator = struct {
// 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)
@ -394,7 +404,7 @@ pub const StackIterator = struct {
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.