SpecConstr number of specializations (-fspec-constr-count)
Hi all, When compiling some program with -O2 using ghc-7.0.1, I got warnings like
SpecConstr Function `$j_s7Xo{v} [lid]' has three call patterns, but the limit is 1 Use -fspec-constr-count=n to set the bound Use -dppr-debug to see specialisations SpecConstr Function `$j_s7YI{v} [lid]' has 7 call patterns, but the limit is 3 Use -fspec-constr-count=n to set the bound Use -dppr-debug to see specialisations
I proceeded to compile with -fspec-constr-count=10, but I still got
SpecConstr Function `$j_s7Xo{v} [lid]' has 7 call patterns, but the limit is 1 Use -fspec-constr-count=n to set the bound Use -dppr-debug to see specialisations
With -fspec-constr-count=55, I got
SpecConstr Function `$j_s7Xo{v} [lid]' has 7 call patterns, but the limit is 6 Use -fspec-constr-count=n to set the bound Use -dppr-debug to see specialisations
Finally, with -fspec-constr-count=56, the warnings disappear. Is this a bug, or is the value of spec-constr-count being manipulated in some way for certain passes? Thanks, Pedro
On 25/11/2010, at 10:33, José Pedro Magalhães wrote:
Is this a bug, or is the value of spec-constr-count being manipulated in some way for certain passes?
spec-constr-count decreases for nested specialisations. For instance, if spec-constr-count is 6 and SpecConstr generates 2 specialisations for a function foo, then spec-constr-count will be 3 for all functions nested in foo. You can turn it off completely with -fno-spec-constr-count. Roman
Hi,
2010/11/25 Roman Leshchinskiy
On 25/11/2010, at 10:33, José Pedro Magalhães wrote:
Is this a bug, or is the value of spec-constr-count being manipulated in some way for certain passes?
spec-constr-count decreases for nested specialisations. For instance, if spec-constr-count is 6 and SpecConstr generates 2 specialisations for a function foo, then spec-constr-count will be 3 for all functions nested in foo. You can turn it off completely with -fno-spec-constr-count.
Ok, thanks! Pedro
Roman
On 25/11/2010 20:01, Roman Leshchinskiy wrote:
On 25/11/2010, at 10:33, José Pedro Magalhães wrote:
Is this a bug, or is the value of spec-constr-count being manipulated in some way for certain passes?
spec-constr-count decreases for nested specialisations. For instance, if spec-constr-count is 6 and SpecConstr generates 2 specialisations for a function foo, then spec-constr-count will be 3 for all functions nested in foo. You can turn it off completely with -fno-spec-constr-count.
The messages are a bit counter-intuitive though - I encountered this recently too, and was baffled by the fact that the suggested flag, -fspec-constr-count, didn't seem to have any effect. Also, these messages should be clearly labelled as warnings, and there should be a way to disable them (I realise they're being generated by the SpecConstr pass and we don't normally generate warnings beyond the desugarer, but still.) Cheers, Simon
participants (3)
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José Pedro Magalhães -
Roman Leshchinskiy -
Simon Marlow