diff options
Diffstat (limited to 'compiler/GHC/CmmToAsm')
| -rw-r--r-- | compiler/GHC/CmmToAsm/X86/CodeGen.hs | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/compiler/GHC/CmmToAsm/X86/CodeGen.hs b/compiler/GHC/CmmToAsm/X86/CodeGen.hs index e9b54c6b45..aa4769f376 100644 --- a/compiler/GHC/CmmToAsm/X86/CodeGen.hs +++ b/compiler/GHC/CmmToAsm/X86/CodeGen.hs @@ -2561,6 +2561,8 @@ genCCall' config is32Bit (PrimTarget (MO_Xchg width)) [dst] [addr, value] _ -- Copy the value into the target register, perform the exchange. let code = toOL [ MOV format (OpReg newval) (OpReg dst_r) + -- On X86 xchg implies a lock prefix if we use a memory argument. + -- so this is atomic. , XCHG format (OpAddr amode) dst_r ] return $ addr_code `appOL` newval_code `appOL` code |