From: Cherry Zhang <cherryyz@google.com>
Date: Sat, 24 Oct 2020 17:05:31 +0000 (-0400)
Subject: cmd/link: preserve alignment for stackmap symbols
X-Git-Tag: go1.16beta1~542
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=404899f6b56800c1d8e0521fc9ce0c856e459d94;p=gostls13.git

cmd/link: preserve alignment for stackmap symbols

Stackmap symbols are content-addressable, so it may be dedup'd
with another symbol with same content. We want stackmap symbols
4-byte aligned. But if it dedup's with another symbol with larger
alignment, preserve that alignment.

Fixes #42071.

Change-Id: I1616dd2b0c175b2aac8f68782a5c7a62053c0b57
Reviewed-on: https://go-review.googlesource.com/c/go/+/264897
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: Than McIntosh <thanm@google.com>
---

diff --git a/src/cmd/link/internal/ld/symtab.go b/src/cmd/link/internal/ld/symtab.go
index dd82963a41..ca688e2011 100644
--- a/src/cmd/link/internal/ld/symtab.go
+++ b/src/cmd/link/internal/ld/symtab.go
@@ -580,8 +580,12 @@ func (ctxt *Link) symtab(pcln *pclntab) []sym.SymKind {
 			symGroupType[s] = sym.SGOFUNC
 			ldr.SetAttrNotInSymbolTable(s, true)
 			ldr.SetCarrierSym(s, symgofunc)
-			const align = 4
-			ldr.SetSymAlign(s, align)
+			align := int32(4)
+			if a := ldr.SymAlign(s); a < align {
+				ldr.SetSymAlign(s, align)
+			} else {
+				align = a
+			}
 			liveness += (ldr.SymSize(s) + int64(align) - 1) &^ (int64(align) - 1)
 		}
 	}