[U-Boot] [PATCH V3 1/2] [NEXT] arm: change relocation flag from -fPIC to -fPIE

Albert Aribaud
2010-09-28T13:14:12Z

Replace GOT indirect addressing with more efficient pic-base
relative addressing for initialized data (uninitialized data
still use GOTi indirect addressing). This also reduces code
size by 0.4% compared to -fPIC.

Signed-off-by: Albert Aribaud <albert.aribaud@free.fr>
---
SUMMARY

This patch aims at optimizing relocatable code both in size and
speed. The first patch switches from '-fPIC' to '-fPIE', which makes
initialized data accesses pc-relative rather than GOT-indirect, and
the second adds '-msingle-pic-base' which factors out GOT addressing
by computing it once and for all.

PATCHSET HISTORY

V1 Initial submission
V2 Compute RAM pic base only if actually relocating
Fixed RAM pic base computation and copy loop
V3 Added fix for tx25

arch/arm/config.mk | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/arm/config.mk b/arch/arm/config.mk
index 6923f6d..138c43a 100644
--- a/arch/arm/config.mk
+++ b/arch/arm/config.mk
@@ -35,7 +35,7 @@ endif

ifndef CONFIG_SYS_ARM_WITHOUT_RELOC
# needed for relocation
-PLATFORM_RELFLAGS += -fPIC
+PLATFORM_RELFLAGS += -fPIE
endif

ifdef CONFIG_SYS_ARM_WITHOUT_RELOC
--
1.7.0.4