tree 5828d77d5f6fb1fcbe932651b71db6f21e479334
parent 7ed2299a8faff3fc13fcd1d2e2daaaa9e371500e
author Renato Golin <renato.golin@linaro.org> 1463088162 +0000
committer Renato Golin <renato.golin@linaro.org> 1463088162 +0000

[ARM] Support and tests for transform of LDR rt, = to MOV

This change implements the transformation in processInstruction() for the
LDR rt, =expression to MOV rt, expression when the expression can be evaluated
and can fit into the immediate field of the MOV or a MVN.

Across the ARM and Thumb instruction sets there are several cases to consider,
each with a different range of representatble constants.

In ARM we have:
 * Modified immediate (All ARM architectures)
 * MOVW (v6t2 and above)

In Thumb we have:
 * Modified immediate (v6t2, v7m and v8m.mainline)
 * MOVW (v6t2, v7m, v8.mainline and v8m.baseline)
 * Narrow Thumb MOV that can be used in an IT block (non flag-setting)

If the immediate fits any of the available alternatives then we make the transformation.

Fixes 25722.

Patch by Peter Smith.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269354 91177308-0d34-0410-b5e6-96231b3b80d8