X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fcmm%2FCmmOpt.hs;h=9a5121541a824a677c9863b5083b4ff66181a72a;hb=8bae799da7444d5debe0ce2e3f3f73692991a59d;hp=a3de41c2c7fbea990a4bb0784ef6b80c308c38de;hpb=28c556a5e0ed5c2687f19ec6ef8853b79ad65518;p=ghc-hetmet.git

diff --git a/compiler/cmm/CmmOpt.hs b/compiler/cmm/CmmOpt.hs
index a3de41c..9a51215 100644
--- a/compiler/cmm/CmmOpt.hs
+++ b/compiler/cmm/CmmOpt.hs
@@ -339,6 +339,38 @@ cmmMachOpFold (MO_Add _) [CmmLit (CmmInt i rep), CmmLit (CmmLabel lbl)]
 cmmMachOpFold (MO_Sub _) [CmmLit (CmmLabel lbl), CmmLit (CmmInt i rep)]
   = CmmLit (CmmLabelOff lbl (fromIntegral (negate (narrowU rep i))))
 
+
+-- Comparison of literal with narrowed/widened operand: perform
+-- the comparison at a different width, as long as the literal is
+-- within range.
+
+#if i386_TARGET_ARCH || x86_64_TARGET_ARCH
+-- powerPC NCG has a TODO for I8/I16 comparisons, so don't try
+
+cmmMachOpFold cmp [CmmMachOp conv [x], CmmLit (CmmInt i _)]
+  | Just (rep, narrow) <- maybe_conversion conv,
+    Just narrow_cmp <- maybe_comparison cmp rep,
+    let narrow_i = narrow rep i,
+    narrow_i == i
+  = cmmMachOpFold narrow_cmp [x, CmmLit (CmmInt narrow_i rep)]
+ where
+    maybe_conversion (MO_U_Conv from _) = Just (from, narrowU)
+    maybe_conversion (MO_S_Conv from _) = Just (from, narrowS)
+    maybe_conversion _ = Nothing
+    
+    maybe_comparison (MO_U_Gt _) rep = Just (MO_U_Gt rep)
+    maybe_comparison (MO_U_Ge _) rep = Just (MO_U_Ge rep)
+    maybe_comparison (MO_U_Lt _) rep = Just (MO_U_Lt rep)
+    maybe_comparison (MO_U_Le _) rep = Just (MO_U_Le rep)
+    maybe_comparison (MO_S_Gt _) rep = Just (MO_S_Gt rep)
+    maybe_comparison (MO_S_Ge _) rep = Just (MO_S_Ge rep)
+    maybe_comparison (MO_S_Lt _) rep = Just (MO_S_Lt rep)
+    maybe_comparison (MO_S_Le _) rep = Just (MO_S_Le rep)
+    maybe_comparison (MO_Eq   _) rep = Just (MO_Eq   rep)
+    maybe_comparison _ _ = Nothing
+
+#endif
+
 -- We can often do something with constants of 0 and 1 ...
 
 cmmMachOpFold mop args@[x, y@(CmmLit (CmmInt 0 _))]
@@ -533,4 +565,4 @@ maybeInvertConditionalExpr (CmmMachOp op args)
 maybeInvertConditionalExpr _ = Nothing
 
 isPicReg (CmmReg (CmmGlobal PicBaseReg)) = True
-isPicReg _ = False
\ No newline at end of file
+isPicReg _ = False