Changes in directory llvm/lib/Target/X86:
README.txt updated: 1.116 -> 1.117
---
Log message:
Add a note that Nate noticed.
---
Diffs of the changes: (+34 -0)
README.txt | 34 ++++++++++++++++++++++++++++++++++
1 files changed, 34 insertions(+)
Index: llvm/lib/Target/X86/README.txt
diff -u llvm/lib/Target/X86/README.txt:1.116
llvm/lib/Target/X86/README.txt:1.117
--- llvm/lib/Target/X86/README.txt:1.116 Sun Jun 4 04:08:00 2006
+++ llvm/lib/Target/X86/README.txt Thu Jun 15 16:33:31 2006
@@ -668,3 +668,37 @@
//===---------------------------------------------------------------------===//
We should handle __attribute__ ((__visibility__ ("hidden"))).
+
+//===---------------------------------------------------------------------===//
+
+Consider:
+int foo(int *a, int t) {
+int x;
+for (x=0; x<40; ++x)
+ t = t + a[x] + x;
+return t;
+}
+
+We generate:
+LBB1_1: #cond_true
+ movl %ecx, %esi
+ movl (%edx,%eax,4), %edi
+ movl %esi, %ecx
+ addl %edi, %ecx
+ addl %eax, %ecx
+ incl %eax
+ cmpl $40, %eax
+ jne LBB1_1 #cond_true
+
+GCC generates:
+
+L2:
+ addl (%ecx,%edx,4), %eax
+ addl %edx, %eax
+ addl $1, %edx
+ cmpl $40, %edx
+ jne L2
+
+Smells like a register coallescing/reassociation issue.
+
+//===---------------------------------------------------------------------===//
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