Changes in directory llvm/lib/Target/X86:
README.txt updated: 1.155 -> 1.156
---
Log message:
more notes
---
Diffs of the changes: (+26 -3)
README.txt | 29 ++++++++++++++++++++++++++---
1 files changed, 26 insertions(+), 3 deletions(-)
Index: llvm/lib/Target/X86/README.txt
diff -u llvm/lib/Target/X86/README.txt:1.155
llvm/lib/Target/X86/README.txt:1.156
--- llvm/lib/Target/X86/README.txt:1.155 Mon Feb 12 14:26:34 2007
+++ llvm/lib/Target/X86/README.txt Mon Feb 12 15:20:26 2007
@@ -874,15 +874,15 @@
if (X) abort();
}
-is currently compiled to (with -static):
+is currently compiled to:
_test:
subl $12, %esp
cmpl $0, 16(%esp)
- jne LBB1_1 #cond_true
+ jne LBB1_1
addl $12, %esp
ret
-LBB1_1: #cond_true
+LBB1_1:
call L_abort$stub
It would be better to produce:
@@ -895,5 +895,28 @@
ret
This can be applied to any no-return function call that takes no arguments etc.
+Alternatively, the stack save/restore logic could be shrink-wrapped, producing
+something like this:
+
+_test:
+ cmpl $0, 4(%esp)
+ jne LBB1_1
+ ret
+LBB1_1:
+ subl $12, %esp
+ call L_abort$stub
+
+Both are useful in different situations. Finally, it could be shrink-wrapped
+and tail called, like this:
+
+_test:
+ cmpl $0, 4(%esp)
+ jne LBB1_1
+ ret
+LBB1_1:
+ pop %eax # realign stack.
+ call L_abort$stub
+
+Though this probably isn't worth it.
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