From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Lance Taylor To: rth@cygnus.com Cc: cort@attis.cs.nmt.edu, gas2@sourceware.cygnus.com Subject: Re: ppc instructions in gas Date: Thu, 06 May 1999 20:06:00 -0000 Message-id: <19990507030530.10843.qmail@daffy.airs.com> References: <19990504180843.A31050@attis.cs.nmt.edu> <19990505145806.H9469@cygnus.com> <19990505165232.A8594@attis.cs.nmt.edu> <19990506150724.A10994@cygnus.com> <19990506150724.A10994@cygnus.com> X-SW-Source: 1999/msg00101.html Date: Thu, 6 May 1999 15:07:24 -0700 From: Richard Henderson On Wed, May 05, 1999 at 04:52:32PM -0600, Cort Dougan wrote: > The signed change at the top makes sense with what the manual says. The > operand in questions should be a 16-bit unsigned immediate value not signed > (as it was before). [...] > /* The SI field in a D form instruction when we accept a wide range > of positive values. */ > #define SISIGNOPT SI + 1 > - { 16, 0, 0, 0, PPC_OPERAND_SIGNED | PPC_OPERAND_SIGNOPT }, > + { 16, 0, 0, 0, /*PPC_OPERAND_SIGNED |*/ PPC_OPERAND_SIGNOPT }, Looking at this again, I wonder if this change is correct. Which instruction were you trying to fix? "liu" perhaps? As-is, it affects instructions like "addis", and you can't really add +50000, can you? We specifically want to accept a wide range of values, because users in practice use a wide range of values. That is, users in practice use lis 4,-0x8000 lis 4,0x7fff lis 4,0xffff lis 4,-1 and expect them all to work. It's true that the PowerPC docs prohibit the last one. However, people use it in real code, so gas accepts it. The last two instructions above generate the same bytes. I don't have the context of the original message. The addis/lis instruction is documented to take a signed operand. I don't know why it makes sense to remove PPC_OPERAND_SIGNED. Ian