diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2f0ab448b1d..69015e90b53 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2001-04-11  Mark Mitchell  <mark@codesourcery.com>
+
+	* Makefile.in (gcse.o): Depend on params.h.
+	* gcse.c: Include params.h.
+	(gcse_main): Don't do GCSE if doing so will take inordinate
+	amounts of memory.
+	* params.def (PARAM_MAX_GCSE_MEMORY): New  parameter.
+	* params.h (MAX_GCSE_MEMORY): New macro.
+
 2001-04-11  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* Makefile.in (insn-output.o): Depend on $(EXPR_H).
diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index c94eb08f462..04757de7bc3 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -1465,7 +1465,7 @@ cse.o : cse.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) $(REGS_H) hard-reg-set.h flags.h
    $(BASIC_BLOCK_H) $(GGC_H) $(TM_P_H)
 gcse.o : gcse.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) $(REGS_H) hard-reg-set.h \
    flags.h real.h insn-config.h ggc.h $(RECOG_H) $(EXPR_H) $(BASIC_BLOCK_H) \
-   function.h output.h toplev.h $(TM_P_H)
+   function.h output.h toplev.h $(TM_P_H) params.h
 sibcall.o : sibcall.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) $(REGS_H) function.h \
    hard-reg-set.h flags.h insn-config.h $(RECOG_H) $(BASIC_BLOCK_H)
 resource.o : resource.c $(CONFIG_H) $(RTL_H) hard-reg-set.h $(SYSTEM_H) \
diff --git a/gcc/gcse.c b/gcc/gcse.c
index 9121af7cb74..402e85e787e 100644
--- a/gcc/gcse.c
+++ b/gcc/gcse.c
@@ -160,6 +160,7 @@ Boston, MA 02111-1307, USA.  */
 #include "function.h"
 #include "expr.h" 
 #include "ggc.h"
+#include "params.h"
 
 #include "obstack.h"
 #define obstack_chunk_alloc gmalloc
@@ -767,6 +768,19 @@ gcse_main (f, file)
       return 0;
     }
 
+  /* If allocating memory for the cprop bitmap would take up too much
+     storage it's better just to disable the optimization.  */
+  if ((n_basic_blocks 
+       * SBITMAP_SET_SIZE (max_gcse_regno)
+       * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
+    {
+      if (warn_disabled_optimization)
+	warning ("GCSE disabled: %d basic blocks and %d registers",
+		 n_basic_blocks, max_gcse_regno);
+
+      return 0;
+    }
+
   /* See what modes support reg/reg copy operations.  */
   if (! can_copy_init_p)
     {
diff --git a/gcc/params.def b/gcc/params.def
index aae706839ed..749414f6e9c 100644
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -66,6 +66,13 @@ DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 	 "The maximum number of instructions to consider to find accurate live register information",
 	 333)
 
+/* The GCSE optimization will be disabled if it would require
+   significantly more memory than this value.  */
+DEFPARAM(PARAM_MAX_GCSE_MEMORY,
+	 "max-gcse-memory",
+	 "The maximum amount of memory to be allocated by GCSE",
+	 50 * 1024 * 1024)
+
 /*
 Local variables:
 mode:c
diff --git a/gcc/params.h b/gcc/params.h
index d5336f2c70d..d97e7bbc396 100644
--- a/gcc/params.h
+++ b/gcc/params.h
@@ -88,5 +88,7 @@ typedef enum compiler_param
   PARAM_VALUE (PARAM_MAX_DELAY_SLOT_INSN_SEARCH)
 #define MAX_DELAY_SLOT_LIVE_SEARCH \
   PARAM_VALUE (PARAM_MAX_DELAY_SLOT_LIVE_SEARCH)
+#define MAX_GCSE_MEMORY \
+  ((size_t) PARAM_VALUE (PARAM_MAX_GCSE_MEMORY))
 
 #endif /* PARAMS_H */