[llvm-commits] [llvm] r64093 - /llvm/trunk/lib/Target/X86/README.txt

[Chris Lattner]

Author: lattner
Date: Sun Feb  8 14:44:19 2009
New Revision: 64093

URL: http://llvm.org/viewvc/llvm-project?rev=64093&view=rev
Log:
add a note.

Modified:
    llvm/trunk/lib/Target/X86/README.txt

Modified: llvm/trunk/lib/Target/X86/README.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/README.txt?rev=64093&r1=64092&r2=64093&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/README.txt (original)
+++ llvm/trunk/lib/Target/X86/README.txt Sun Feb  8 14:44:19 2009
@@ -1831,3 +1831,34 @@
 
 //===---------------------------------------------------------------------===//
 
+We currently compile this:
+
+define i32 @func1(i32 %v1, i32 %v2) nounwind {
+entry:
+  %t = call {i32, i1} @llvm.sadd.with.overflow.i32(i32 %v1, i32 %v2)
+  %sum = extractvalue {i32, i1} %t, 0
+  %obit = extractvalue {i32, i1} %t, 1
+  br i1 %obit, label %overflow, label %normal
+normal:
+  ret i32 %sum
+overflow:
+  call void @llvm.trap()
+  unreachable
+}
+declare {i32, i1} @llvm.sadd.with.overflow.i32(i32, i32)
+declare void @llvm.trap()
+
+to:
+
+_func1:
+	movl	4(%esp), %eax
+	addl	8(%esp), %eax
+	jo	LBB1_2	## overflow
+LBB1_1:	## normal
+	ret
+LBB1_2:	## overflow
+	ud2
+
+it would be nice to produce "into" someday.
+
+//===---------------------------------------------------------------------===//