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[3/5] PRU: Fix comment about R3/RA

Message ID 20191013084454.13878-4-dimitar@dinux.eu
State New
Headers show
Series Assorted minor cleanups for PRU backend | expand

Commit Message

Dimitar Dimitrov Oct. 13, 2019, 8:44 a.m. UTC 
Comment had a typo.  Fix it and clarify.

gcc/ChangeLog:

2019-10-13  Dimitar Dimitrov  <dimitar@dinux.eu>

	* config/pru/pru.h: Clarify R3/RA ABI.

Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>
---
 gcc/config/pru/pru.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
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Patch

diff --git a/gcc/config/pru/pru.h b/gcc/config/pru/pru.h
index 15fb637dec6..f2bdd1ef02b 100644
--- a/gcc/config/pru/pru.h
+++ b/gcc/config/pru/pru.h
@@ -125,7 +125,8 @@ 
    1      r1		  Caller Saved.  Also used as a temporary by function.
 			  profiler and function prologue/epilogue.
    2      r2       sp	  Stack Pointer.
-   3*     r3.w0    ra	  Return Address (16-bit).
+   3*     r3.w0		  ABI does not specify if it is caller or callee saved.
+   3*     r3.w2    ra	  Return Address (16-bit).
    4      r4       fp	  Frame Pointer, also called Argument Pointer in ABI.
    5-13   r5-r13	  Callee Saved Registers.
    14-29  r14-r29	  Register Arguments.  Caller Saved Registers.
@@ -148,6 +149,11 @@ 
    of 8 bit sub-registers (e.g. RA starts at r12).  When outputting assembly,
    GCC will take into account the RTL operand size (e.g. r12:HI) in order to
    translate to the conventional PRU ISA format expected by GAS (r3.w0).
+
+   TI ISA documentation (SPRUHV7C) does not mark r3.w0 as neither
+   caller-saved nor callee-saved.  So until TI clarifies, let's mark
+   it as fixed.
+
 */
 
 #define FIXED_REGISTERS				\