[llvm-commits] [llvm] r91823 - /llvm/trunk/lib/Target/X86/README.txt

[Eli Friedman]

Author: efriedma
Date: Mon Dec 21 02:03:16 2009
New Revision: 91823

URL: http://llvm.org/viewvc/llvm-project?rev=91823&view=rev
Log:
A couple minor README updates.


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=91823&r1=91822&r2=91823&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/README.txt (original)
+++ llvm/trunk/lib/Target/X86/README.txt Mon Dec 21 02:03:16 2009
@@ -123,20 +123,6 @@
 
 //===---------------------------------------------------------------------===//
 
-How about intrinsics? An example is:
-  *res = _mm_mulhi_epu16(*A, _mm_mul_epu32(*B, *C));
-
-compiles to
-	pmuludq (%eax), %xmm0
-	movl 8(%esp), %eax
-	movdqa (%eax), %xmm1
-	pmulhuw %xmm0, %xmm1
-
-The transformation probably requires a X86 specific pass or a DAG combiner
-target specific hook.
-
-//===---------------------------------------------------------------------===//
-
 In many cases, LLVM generates code like this:
 
 _test:
@@ -1762,6 +1748,11 @@
 	cmpl	$150, %edi
 	jne	LBB1_1	## bb1
 
+The issue is that we hoist the cast of "scaler" to long long outside of the
+loop, the value comes into the loop as two values, and
+RegsForValue::getCopyFromRegs doesn't know how to put an AssertSext on the
+constructed BUILD_PAIR which represents the cast value.
+
 //===---------------------------------------------------------------------===//
 
 Test instructions can be eliminated by using EFLAGS values from arithmetic