[OE-core] [PATCH 4/5] tunearch/arm: Differentiate between thumb code generation and thumb capability

[Khem Raj]

We have diverged a bit from oe.dev where thumb in OVERRIDES meant
the code was being compiled in thumb mode. With tunearch this got
a different meaning where it meant that if a core is capable of
generating thumb code them we will have this in overrides. With this
patch I am trying to address the problem where 'thumbmode' in TUNE_FEATURES
means that code will be compiled in thumb mode by default and
'thumb' is to denote that core is capable of thumb instruction set.

Signed-off-by: Khem Raj <raj.khem at gmail.com>
---
 .../conf/machine/include/arm/feature-arm-thumb.inc |   18 ++++++++++++++----
 1 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/meta/conf/machine/include/arm/feature-arm-thumb.inc b/meta/conf/machine/include/arm/feature-arm-thumb.inc
index da29102..cb6f4e7 100644
--- a/meta/conf/machine/include/arm/feature-arm-thumb.inc
+++ b/meta/conf/machine/include/arm/feature-arm-thumb.inc
@@ -4,10 +4,20 @@
 # encoded RISC sub-set. Thumb code is smaller (maybe 70% of the ARM size)
 # but requires more instructions (140% for 70% smaller code) so may be
 # slower.
-TUNEVALID[thumb] = "Use thumb instructions instead of ARM"
-ARM_THUMB_M_OPT = "${@['-marm', '-mthumb'][d.getVar('ARM_INSTRUCTION_SET', 1) == 'thumb']}"
-TUNE_CCARGS += "${@bb.utils.contains("TUNE_FEATURES", "thumb", "${ARM_THUMB_M_OPT}", "", d)}"
-OVERRIDES .= "${@bb.utils.contains("TUNE_FEATURES", "thumb", ":thumb", "", d)}"
+
+# 'thumbmode' in TUNE_FEATURES means default ISA for code generation is thumb
+# 'thumb' in TUNE_FEATURES means the core supports thumb ISA but code
+# generation can happen in arm or thumb
+# having 'thumbmode' would imply 'thumb' naturally
+
+TUNEVALID[thumbmode] = "Use THUMB instruction set instead of ARM"
+ARM_INSTRUCTION_SET ?= "arm"
+AVAILTUNES += "${@bb.utils.contains("ARM_INSTRUCTION_SET", "thumb", "thumbmode", "", d)}"
+TUNE_FEATURES_tune-thumbmode += "${@bb.utils.contains("ARM_INSTRUCTION_SET", "thumb", "thumbmode", "", d)}"
+TUNE_CCARGS += "${@bb.utils.contains("ARM_INSTRUCTION_SET", "thumb", "-mthumb", "-marm", d)}"
+OVERRIDES .= "${@bb.utils.contains("ARM_INSTRUCTION_SET", "thumb", ":thumb", "", d)}"
+
+TUNEVALID[thumb] = "THUMB instruction set capable ARM core"
 
 # Note armv7 will hit on armv7a as well
 ARMPKGSFX_THUMB .= "${@bb.utils.contains("TUNE_FEATURES", [ "armv4", "thumb" ], "t", "", d)}"
-- 
1.7.8.3