On 23/03/13 11:20, Eric Botcazou wrote:
We ran into an ICE at -Os on the 4.7 branch for ARM (BE/VFPv3/ARM):
FAIL: gcc.c-torture/compile/920928-2.c -Os (internal compiler error)
It's an assertion deep in the ARM back-end:
/* If an insn doesn't have a range defined for it, then it isn't
expecting to be reworked by this code. Better to stop now than
to generate duff assembly code. */
gcc_assert (fix->forwards || fix->backwards);
This happens for arm_zero_extendhisi2_v6, but I fail to see what is different
for it from arm_extendhisi2_v6, which is expecting to be reworked.
Hence the attached patch, which copies attributes from arm_extendhisi2_v6 to
arm_zero_extendhisi2_v6. No regressions on ARM, OK for the mainline?
2013-03-23 Eric Botcazou
* config/arm/arm.md (arm_zero_extendhisi2): Add pool_range and
neg_pool_range attributes.
(arm_zero_extendhisi2_v6): Likewise.
Having half-word accesses into the minipool is generally a bad idea.
The limited offset range that's supported by these instructions means
it's much more likely that we'll end up with a pool after a conditional
branch or, worse, in the middle of a linear code sequence. That means
we have to jump around the pool, which costs performance.
We really need to find out why the compiler keeps trying to create these
and fix that problem rather than work around the issue.
I'm not sure why the v6 variants allow this; I thought that had been
taken out.
R.
p.diff
Index: config/arm/arm.md
===
--- config/arm/arm.md (revision 196816)
+++ config/arm/arm.md (working copy)
@@ -4650,7 +4650,9 @@ (define_insn "*arm_zero_extendhisi2"
#
ldr%(h%)\\t%0, %1"
[(set_attr "type" "alu_shift,load_byte")
- (set_attr "predicable" "yes")]
+ (set_attr "predicable" "yes")
+ (set_attr "pool_range" "*,256")
+ (set_attr "neg_pool_range" "*,244")]
)
(define_insn "*arm_zero_extendhisi2_v6"
@@ -4660,8 +4662,10 @@ (define_insn "*arm_zero_extendhisi2_v6"
"@
uxth%?\\t%0, %1
ldr%(h%)\\t%0, %1"
- [(set_attr "predicable" "yes")
- (set_attr "type" "simple_alu_shift,load_byte")]
+ [(set_attr "type" "simple_alu_shift,load_byte")
+ (set_attr "predicable" "yes")
+ (set_attr "pool_range" "*,256")
+ (set_attr "neg_pool_range" "*,244")]
)
(define_insn "*arm_zero_extendhisi2addsi"
