[Mono-bugs] [Bug 58343][Nor] Changed - AOT failure for classpath.dll from ikvm

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Changed by totte@hiddenpeaks.com.

http://bugzilla.ximian.com/show_bug.cgi?id=58343

--- shadow/58343	2004-05-23 11:42:48.000000000 -0400
+++ shadow/58343.tmp.24755	2004-05-23 14:17:30.000000000 -0400
@@ -10,13 +10,12 @@
 Component: misc
 AssignedTo: massi@ximian.com                            
 ReportedBy: vargaz@freemail.hu               
 QAContact: mono-bugs@ximian.com
 TargetMilestone: ---
 URL: 
-Cc: 
 Summary: AOT failure for classpath.dll from ikvm
 
 When running
 
 mono -O=-all --aot classpath.dll
 
@@ -160,6 +159,37 @@
 
 The problem looks like it's due to that a imm8 branch (imm eb) is now 
 out of range (disp 151 and max is -127 to +127 ) probably due to some 
 loop optimizations.
 
 
+
+------- Additional Comments From totte@hiddenpeaks.com  2004-05-23 14:17 -------
+Found the problem,
+
+When loop optimization (that doesn't do any real optimization it 
+self) is enabled the mono_arch_output_basic_block for x86 does 
+padding for loop blocks (could help performance, padding is 8 byte) 
+but for this method it breaks the local branches (because it padds a 
+lot of loop blocks).
+
+To fix the problem we can disable the padding, going to test how it 
+affects performance tomorrow. The code is on line 2105 in mini-x86.c :
+
+	if (cfg->opt & MONO_OPT_LOOP) {
+		int pad, align = 8;
+		/* set alignment depending on cpu */
+		if (bb->nesting && (bb->in_count == 1) && (pad = (cfg-
+>code_len & (align - 1)))) {
+			pad = align - pad;
+			/*g_print ("adding %d pad at %x to loop in %
+s\n", pad, cfg->code_len, cfg->method->name);*/
+			x86_padding (code, pad);
+			cfg->code_len += pad;
+			bb->native_offset = cfg->code_len;
+		}
+	}
+
+If we going to pad we need to insert this code in a earlier phase.
+
+Lupus, comments about performance? maybee better that we work for -
+O=all then having the correct padding?