ARM pc-relative loads

Paul Brook paul@codesourcery.com
Tue May 31 16:49:00 GMT 2011


The patch below fixes a failure observed building a hacked-up variant of the 
linux kernel.

The assembler is failing to resolve a pc-relative Thumb load from a global 
symbol in the same section.  My first guess was that this is a feature - 
symbol preemption requires the address be resolved at dynamic link time.  
However the offset range of pc-relative load instructions is sufficiently 
small that I don't believe that symbol preemption would ever actually succeed 
in practice.

We already resolve the equivalent ARM relocation. Arguably this is a bug. 
However there is code that relies on this behavior. Given the uselessness of 
exporting these relocations I've chosen to go for consistency with ARM LDR, 
and resolve the relocation.  Further investigation revealed a handful of other 
load instructions that also need to be handled.

Tested on arm-none-eabi
Applied to CVS head

Paul

2011-05-31  Paul Brook  <paul@codesourcery.com>

	gas/
	* config/tc-arm.c (arm_force_relocation): Resolve all pc-relative
	loads.

	gas/testsuite/
	* gas/arm/ldr-global.d: New test.
	* gas/arm/ldr-global.s: New test.
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