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author | Björn Gustavsson <[email protected]> | 2012-03-30 11:05:16 +0200 |
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committer | Björn Gustavsson <[email protected]> | 2015-07-03 14:28:03 +0200 |
commit | 45f469ca089096c8a59ca53d948d05d1a998386e (patch) | |
tree | 2da989257d20ae659c7ad8a503d4978e4b6b7a3f /HOWTO/INSTALL.md | |
parent | 54189af4a519b72883dde3263135baf6aba0f81f (diff) | |
download | otp-45f469ca089096c8a59ca53d948d05d1a998386e.tar.gz otp-45f469ca089096c8a59ca53d948d05d1a998386e.tar.bz2 otp-45f469ca089096c8a59ca53d948d05d1a998386e.zip |
Change the meaning of 'x' in a transformation
The purpose of this series of commits is to improve code generation
for the Clang compiler.
As a first step we want to change the meaning of 'x' in a
transformation such as:
operation Literal=q => move Literal x | operation x
Currently, a plain 'x' means reg[0] or x(0), which is the first
element in the X register array. That element is distinct from
r(0) which is a variable in process_main(). Therefore, since r(0)
and x(0) are currently distinct it is fine to use x(0) as a
scratch register.
However, in the next commit we will eliminate the separate variable
for storing the contents of X register zero (thus, x(0) and r(0)
will point to the same location in the X register array). Therefore,
we must use another scratch register in transformation. Redefine
a plain 'x' in a transformation to mean x(1023). Also define
SCRATCH_X_REG so that we can refer to the register by name from
C code.
Diffstat (limited to 'HOWTO/INSTALL.md')
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