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Calling Conventions Non-Floating Point Registers

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2.2.1: Non-Floating Point Registers

The PowerPC architecture defines thirty-two non-floating point registers directly visible to the programmer. In thirty-two bit implementations, each register is thirty-two bits wide. In sixty-four bit implementations, each register is sixty-four bits wide.

These registers are referred to as gpr0 to gpr31.

Some of the registers serve defined roles in the EABI programming model. The following table describes the role of each of these registers:

Register Name Alternate Name Description
r1 sp stack pointer
r2 na global pointer to the Small Constant Area (SDA2)
r3 - r12 NA parameter and result passing
r13 NA global pointer to the Small Data Area (SDA)


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