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Compiler User Guide

Conventions and Feedback Overview of the Compiler Getting Started with the Compiler Compiler Features Compiler Coding Practices Compiler Diagnostic Messages Using the Inline and Embedded Assemblers of the AR Compiler support for inline assembly language Inline assembler support in the compiler Restrictions on inline assembler support in the co Inline assembly language syntax with the __asm key Inline assembly language syntax with the asm keywo Inline assembler rules for compiler keywords __asm Restrictions on inline assembly operations in C an Inline assembler register restrictions in C and C+ Inline assembler processor mode restrictions in C Inline assembler Thumb instruction set restriction Inline assembler Vector Floating-Point (VFP) restr Inline assembler instruction restrictions in C and Miscellaneous inline assembler restrictions in C a Inline assembler and register access in C and C++ Inline assembler and the # constant expression spe Inline assembler and instruction expansion in C an Expansion of inline assembler instructions that us Expansion of inline assembler load and store instr Inline assembler effect on processor condition fla Inline assembler operands in C and C++ code Inline assembler expression operands in C and C++ Inline assembler register list operands in C and C Inline assembler intermediate operands in C and C+ Inline assembler function calls and branches in C Behavior of BL and SVC without optional lists in C Inline assembler BL and SVC input parameter list i Inline assembler BL and SVC output value list in C Inline assembler BL and SVC corrupted register lis Inline assembler branches and labels in C and C++ Inline assembler and virtual registers Embedded assembler support in the compiler Embedded assembler syntax in C and C++ Effect of compiler ARM and Thumb states on embedde Restrictions on embedded assembly language functio Compiler generation of embedded assembly language Access to C and C++ compile-time constant expressi Differences between expressions in embedded assemb Manual overload resolution in embedded assembler __offsetof_base keyword for related base classes i Compiler-supported keywords for calling class memb __mcall_is_virtual(D, f) __mcall_is_in_vbase(D, f) __mcall_offsetof_vbase(D, f) __mcall_this_offset(D, f) __vcall_offsetof_vfunc(D, f) Calling nonstatic member functions in embedded ass Calling a nonvirtual member function Calling a virtual member function Legacy inline assembler that accesses sp, lr, or p Accessing sp (r13), lr (r14), and pc (r15) in lega Differences in compiler support of inline and embe

Expansion of inline assembler load and store instructions

Expansion of inline assembler load and store instructions

The LDM, STM, LDRD, and STRD instructions might be replaced by equivalent ARM instructions. In this case the compiler outputs a warning message informing you that it might expand instructions. The warning can be suppressed with --diag_suppress.

Inline assembly code must be written in such a way that it does not depend on the number of expected instructions or on the expected execution time for each specified instruction.

Instructions that normally place constraints on pairs of operand registers, such as LDRD and STRD, are replaced by a sequence of instructions with equivalent functionality and without the constraints. However, these might be recombined into LDRD and STRD instructions.

All LDM and STM instructions are expanded into a sequence of LDR and STR instructions with equivalent effect. However, the compiler might subsequently recombine the separate instructions into an LDM or STM during optimization.

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