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From: gonz@ratloop.com To: gcc-gnats@gcc.gnu.org Subject: optimization/10396: Constraint alternatives cause error " `asm' operand requires impossible reload" Date: Mon, 14 Apr 2003 04:06:00 -0000 [thread overview] Message-ID: <20030414040524.11372.qmail@sources.redhat.com> (raw) >Number: 10396 >Category: optimization >Synopsis: Constraint alternatives cause error " `asm' operand requires impossible reload" >Confidential: no >Severity: non-critical >Priority: medium >Responsible: unassigned >State: open >Class: sw-bug >Submitter-Id: net >Arrival-Date: Mon Apr 14 04:06:01 UTC 2003 >Closed-Date: >Last-Modified: >Originator: Pete Gonzalez >Release: GCC 3.2.1 (cross compiler) >Organization: >Environment: This is a custom build of GCC on Win32 Cygwin, with target CPU arm7tdmi. I am using the C++ front end. >Description: When compiling with optimizations (-O2 or -O3), the function below sometimes causes GCC to fail with the error message "`asm' operand requires impossible reload". The function compiles fine by itself and also in simple contexts; it seems that the error only occurs in complex inlining situations. The error goes away if I reduce the constraints to a single alternative (instead of 3). It does not matter which of the three I choose, which suggests that my constraint expressions are valid. The "impossible reload" message is coming from line 3933 of gcc/reload1.c, but I can't find any documentation on this error. _____________________________ inline int multiplyFixedPoint(int mantissaA,int mantissaB) { int result; int temp; asm("\n\ smull %0, %1, %2, %3 \n\ mov %0, %0, lsr #16 \n\ orr %0, %0, %1, lsl #16 \n\ " : "=&r,&r,&r"(result), "=&r,&r,&r"(temp) // outputs : "%r,r,r"(mantissaA), "0,1,r"(mantissaB) // inputs : "cc" // clobbered ); return result; } >How-To-Repeat: If someone is interested in pursuing this, I can isolate some source code that reproduces the problem. However, the situations which expose the bug might depend on the particular build of GCC. >Fix: >Release-Note: >Audit-Trail: >Unformatted:
next reply other threads:[~2003-04-14 4:06 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2003-04-14 4:06 gonz [this message] 2003-04-14 7:23 steven
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