Add a new static flag -fno-opt-coercion

This just disables the coercion optimiser, mainly for measurements in the paper

4 files changed, 17 insertions, 3 deletions

diff --git a/compiler/main/StaticFlagParser.hs b/compiler/main/StaticFlagParser.hs
index 803babaf50..54f0a92115 100644
--- a/compiler/main/StaticFlagParser.hs
+++ b/compiler/main/StaticFlagParser.hs
@@ -185,6 +185,7 @@ isStaticFlag f =
     "fsimple-list-literals",
     "fruntime-types",
     "fno-pre-inlining",
+    "fno-opt-coercion",
     "fexcess-precision",
     "static",
     "fhardwire-lib-paths",
diff --git a/compiler/main/StaticFlags.hs b/compiler/main/StaticFlags.hs
index 96f8b4b715..049b61fedb 100644
--- a/compiler/main/StaticFlags.hs
+++ b/compiler/main/StaticFlags.hs
@@ -24,7 +24,7 @@ module StaticFlags (
 	opt_PprCols,
 	opt_PprCaseAsLet,
 	opt_PprStyle_Debug, opt_TraceLevel,
-        opt_NoDebugOutput,
+        opt_NoDebugOutput, 
 
 	-- Suppressing boring aspects of core dumps
 	opt_SuppressAll,
@@ -52,6 +52,7 @@ module StaticFlags (
 	opt_CprOff,
 	opt_SimplNoPreInlining,
 	opt_SimplExcessPrecision,
+	opt_NoOptCoercion,
 	opt_MaxWorkerArgs,
 
 	-- Unfolding control
@@ -266,7 +267,6 @@ opt_Fuel                        = lookup_def_int "-dopt-fuel" maxBound
 opt_NoDebugOutput   :: Bool
 opt_NoDebugOutput               = lookUp  (fsLit "-dno-debug-output")
 
-
 -- profiling opts
 opt_SccProfilingOn :: Bool
 opt_SccProfilingOn		= lookUp  (fsLit "-fscc-profiling")
@@ -320,6 +320,9 @@ opt_SimplNoPreInlining		= lookUp  (fsLit "-fno-pre-inlining")
 opt_SimplExcessPrecision :: Bool
 opt_SimplExcessPrecision	= lookUp  (fsLit "-fexcess-precision")
 
+opt_NoOptCoercion :: Bool
+opt_NoOptCoercion    	        = lookUp  (fsLit "-fno-opt-coercion")
+
 -- Unfolding control
 -- See Note [Discounts and thresholds] in CoreUnfold
 
diff --git a/compiler/types/OptCoercion.lhs b/compiler/types/OptCoercion.lhs
index 0fff7abc59..26f3295b28 100644
--- a/compiler/types/OptCoercion.lhs
+++ b/compiler/types/OptCoercion.lhs
@@ -19,6 +19,7 @@ import Var
 import VarSet

 import VarEnv

 import PrelNames

+import StaticFlags	( opt_NoOptCoercion )

 import Util

 import Outputable

 \end{code}

@@ -50,7 +51,9 @@ mkCoPredTy in the ForAll case, where this note appears.
 optCoercion :: TvSubst -> Coercion -> NormalCo

 -- ^ optCoercion applies a substitution to a coercion, 

 --   *and* optimises it to reduce its size

-optCoercion env co = opt_co env False co

+optCoercion env co 

+  | opt_NoOptCoercion = substTy env co

+  | otherwise         = opt_co env False co

 

 type NormalCo = Coercion

   -- Invariants: 

diff --git a/docs/users_guide/flags.xml b/docs/users_guide/flags.xml
index f5f949a100..ad219cfa4e 100644
--- a/docs/users_guide/flags.xml
+++ b/docs/users_guide/flags.xml
@@ -1551,6 +1551,13 @@ phase <replaceable>n</replaceable></entry>
 	    </row>
 
 	    <row>
+	      <entry><option>-fno-opt-coercion</option></entry>
+	      <entry>Turn off the coercion optimiser</entry>
+	      <entry>static</entry>
+	      <entry>-</entry>
+	    </row>
+
+	    <row>
 	      <entry><option>-feager-blackholing</option></entry>
 	      <entry>Turn on <link linkend="parallel-compile-options">eager blackholing</link></entry>
 	      <entry>dynamic</entry>