Ibm binary incompatible problem between gcc and xl compilers for vector data types
Generate code that tries to avoid not avoid the use of indexed load or store instructions. These instructions can incur a performance penalty on Power6 processors in certain situations, such as when stepping through large arrays that cross a 16M boundary. This option is enabled by default when targeting Power6 and disabled otherwise. Generate code that uses does not use the floating-point multiply and accumulate instructions.
These instructions are generated by default if hardware floating point is used. Generate code that uses does not use the half-word multiply and multiply-accumulate instructions on the IBM , , and processors. These instructions are generated by default when targeting those processors. This instruction is generated by default when targeting those processors. For example, by default a structure containing nothing but 8 unsigned bit-fields of length 1 is aligned to a 4-byte boundary and has a size of 4 bytes.
By using -mno-bit-align , the structure is aligned to a 1-byte boundary and is 1 byte in size. Generate code that allows does not allow a static executable to be relocated to a different address at run time. A simple embedded PowerPC system loader should relocate the entire contents of. For this to work, all objects linked together must be compiled with -mrelocatable or -mrelocatable-lib.
Like -mrelocatable , -mrelocatable-lib generates a. Objects compiled with -mrelocatable-lib may be linked with objects compiled with any combination of the -mrelocatable options. The -mlittle-endian option is the same as -mlittle. The -mbig-endian option is the same as -mbig.
On Darwin and Mac OS X systems, compile code so that it is not relocatable, but that its external references are relocatable. The resulting code is suitable for applications, but not shared libraries. Treat the register used for PIC addressing as read-only, rather than loading it in the prologue for each function. The runtime system is responsible for initializing this register with an appropriate value before execution begins. This option controls the priority that is assigned to dispatch-slot restricted instructions during the second scheduling pass.
This option controls which dependences are considered costly by the target during instruction scheduling. This option controls which NOP insertion scheme is used during the second scheduling pass. The argument scheme takes one of the following values:.
Insert NOPs to force costly dependent insns into separate groups. Insert exactly as many NOPs as needed to force an insn to a new group, according to the estimated processor grouping. Insert number NOPs to force an insn to a new group. Select the type of traceback table.
Extend the current ABI with a particular extension, or remove such extension. This is not likely to work if your system defaults to using IEEE extended-precision long double. If you change the long double type from IEEE extended-precision, the compiler will issue a warning unless you use the -Wno-psabi option. This is not likely to work if your system defaults to using IBM extended-precision long double. If you change the long double type from IBM extended-precision, the compiler will issue a warning unless you use the -Wno-psabi option.
Overriding the default ABI requires special system support and is likely to fail in spectacular ways.
Otherwise, the compiler must insert an instruction before every non-prototyped call to set or clear bit 6 of the condition code register CR to indicate whether floating-point values are passed in the floating-point registers in case the function takes variable arguments. With -mprototype , only calls to prototyped variable argument functions set or clear the bit. On embedded PowerPC systems, assume that the startup module is called sim-crt0. On embedded PowerPC systems, assume that the startup module is called crt0.
Selecting -mno-eabi means that the stack is aligned to a byte boundary, no EABI initialization function is called from main , and the -msdata option only uses r13 to point to a single small data area. Put small initialized non- const global and static data in the.
Put small uninitialized global and static data in the. Put small uninitialized global data in the. Do not use register r13 to address small data however. This is the default behavior unless other -msdata options are used.
On embedded PowerPC systems, put all initialized global and static data in the. Inline all block moves such as calls to memcpy or structure copies less than or equal to num bytes. The minimum value for num is 32 bytes on bit targets and 64 bytes on bit targets. The default value is target-specific. Generate non-looping inline code for all block compares such as calls to memcmp or structure compares less than or equal to num bytes. If num is 0, all inline expansion non-loop and loop of block compare is disabled.
Generate an inline expansion using loop code for all block compares that are less than or equal to num bytes, but greater than the limit for non-loop inline block compare expansion. If the block length is not constant, at most num bytes will be compared before memcmp is called to compare the remainder of the block. Generate at most num pairs of load instructions to compare the string inline. If the difference or end of string is not found at the end of the inline compare a call to strcmp or strncmp will take care of the rest of the comparison.
The default is 8 pairs of loads, which will compare 64 bytes on a bit target and 32 bytes on a bit target. By default, num is 8. The -G num switch is also passed to the linker. All modules should be compiled with the same -G num value. By default assume that all calls are far away so that a longer and more expensive calling sequence is required.
This is required for calls farther than 32 megabytes 33,, bytes from the current location. A short call is generated if the compiler knows the call cannot be that far away. This setting can be overridden by the shortcall function attribute, or by pragma longcall 0. Some linkers are capable of detecting out-of-range calls and generating glue code on the fly.
On these systems, long calls are unnecessary and generate slower code. The two target addresses represent the callee and the branch island. The branch island is appended to the body of the calling function; it computes the full bit address of the callee and jumps to it. On Mach-O Darwin systems, this option directs the compiler emit to the glue for every direct call, and the Darwin linker decides whether to use or discard it.
In the future, GCC may ignore all longcall specifications when the linker is known to generate glue. The relocation allows the linker to reliably associate function call with argument setup instructions for TLS optimization, which in turn allows GCC to better schedule the sequence.
This option enables use of the reciprocal estimate and reciprocal square root estimate instructions with additional Newton-Raphson steps to increase precision instead of doing a divide or square root and divide for floating-point arguments. You should use the -ffast-math option when using -mrecip or at least -funsafe-math-optimizations , -ffinite-math-only , -freciprocal-math and -fno-trapping-math. Note that while the throughput of the sequence is generally higher than the throughput of the non-reciprocal instruction, the precision of the sequence can be decreased by up to 2 ulp i.
This option controls which reciprocal estimate instructions may be used. Enable the reciprocal square root approximation instructions for both single and double precision. Assume do not assume that the reciprocal estimate instructions provide higher-precision estimates than is mandated by the PowerPC ABI. The double-precision square root estimate instructions are not generated by default on low-precision machines, since they do not provide an estimate that converges after three steps.
Specifies the ABI type to use for vectorizing intrinsics using an external library. GCC currently emits calls to acosd2 , acosf4 , acoshd2 , acoshf4 , asind2 , asinf4 , asinhd2 , asinhf4 , atan2d2 , atan2f4 , atand2 , atanf4 , atanhd2 , atanhf4 , cbrtd2 , cbrtf4 , cosd2 , cosf4 , coshd2 , coshf4 , erfcd2 , erfcf4 , erfd2 , erff4 , exp2d2 , exp2f4 , expd2 , expf4 , expm1d2 , expm1f4 , hypotd2 , hypotf4 , lgammad2 , lgammaf4 , log10d2 , log10f4 , log1pd2 , log1pf4 , log2d2 , log2f4 , logd2 , logf4 , powd2 , powf4 , sind2 , sinf4 , sinhd2 , sinhf4 , sqrtd2 , sqrtf4 , tand2 , tanf4 , tanhd2 , and tanhf4 when generating code for power7.
Both -ftree-vectorize and -funsafe-math-optimizations must also be enabled. The MASS libraries must be specified at link time. Generate do not generate the friz instruction when the -funsafe-math-optimizations option is used to optimize rounding of floating-point values to bit integer and back to floating point.
As with Fortran 95, this is intended to be a minor upgrade, incorporating clarifications and corrections to Fortran , as well as introducing a select few new capabilities. Proposed new capabilities include. A full list is in the report "The language features that have been chosen for Fortran " PDF file. Since Fortran has been around for nearly fifty years, there is a vast body of Fortran in daily use throughout the scientific and engineering communities.
It is the primary language for some of the most intensive supercomputing tasks, such as weather and climate modeling , computational fluid dynamics , computational chemistry , quantum chromodynamics , simulations of long-term solar system dynamics , high-fidelity evolution artificial satellite orbits , and simulation of automobile crash dynamics. Indeed, one finds that even today, half a century later, floating-point benchmarks to gauge the performance of new computer processors are still written in Fortran e.
The Fortran language features described are intended to be a fairly comprehensive overview of the Fortran language; full details may be found in any of several Fortran textbooks.
Only those features widely used in new programs are described, as few of the historic features are used in modern programs. Still, most have been retained in the language to maintain backward compatibility. Portability was a problem in the early days because there was no agreed standard—not even IBM's reference manual—and computer companies vied to differentiate their offerings from others by providing incompatible features.
Standards have improved portability. The standard provided a reference syntax and semantics, but vendors continued to provide incompatible extensions.
Government were required to diagnose extensions of the standard. Rather than offer two processors, essentially every compiler eventually had at least an option to diagnose extensions. Incompatible extensions were not the only portability problem.
For numerical calculations, it is important to take account of the characteristics of the arithmetic. This was addressed by Fox et. The ideas therein became widely used, and were eventually incorporated into the standard by way of intrinsic inquiry functions. The widespread now almost universal adoption of the IEEE standard for binary floating-point arithmetic has essentially removed this problem.
Access to the computing environment e. Large collections of "library" software that could be described as being loosely-related to engineering and scientific calculations, such as graphics libraries, have been written in C, and therefore access to them presented a portability problem. This has been addressed by incorporation of C interoperability into the standard. It is now possible and relatively easy to write an entirely portable program in Fortran, even without recourse to a preprocessor.
Vendors of high-performance scientific computers e. Object-Oriented Fortran was an object-oriented extension of Fortran, in which data items can be grouped into objects, which can be instantiated and executed in parallel. Such machine-specific extensions have either disappeared over time or have had elements incorporated into the main standards; the major remaining extension is OpenMP , which is a cross-platform extension for shared memory programming.
One new extension, CoArray Fortran , is intended to support parallel programming. The Fortran Standard includes an optional Part 3 which defines an optional conditional compilation capability. This capability is often referred to as "CoCo". Many Fortran compilers have integrated subsets of the C preprocessor into their systems. The sample programs can be compiled and run with any standard Fortran compiler see the end of this article for lists of compilers. Most modern Fortran compilers expect a file with a.
The fundamental unit of program is the basic block ; a basic block is a stretch of program which has a single entry point and a single exit point. The purpose of section 4 is to prepare for section 5 a table of predecessors PRED table which enumerates the basic blocks and lists for every basic block each of the basic blocks which can be its immediate predecessor in flow, together with the absolute frequency of each such basic block link.
From Wikipedia, the free encyclopedia Redirected from Fortran programming language. For more details on this topic, see Fortran language features.