[X86] Optimize stackmap shadows on X86.
This patch minimizes the number of nops that must be emitted on X86 to satisfy
stackmap shadow constraints.
To minimize the number of nops inserted, the X86AsmPrinter now records the
size of the most recent stackmap's shadow in the StackMapShadowTracker class,
and tracks the number of instruction bytes emitted since the that stackmap
instruction was encountered. Padding is emitted (if it is required at all)
immediately before the next stackmap/patchpoint instruction, or at the end of
the basic block.
This optimization should reduce code-size and improve performance for people
using the llvm stackmap intrinsic on X86.
<rdar://problem/14959522>
llvm-svn: 213892
diff --git a/llvm/test/MC/X86/stackmap-nops.ll b/llvm/test/MC/X86/stackmap-nops.ll
index 98d17ea..2b0b88c 100644
--- a/llvm/test/MC/X86/stackmap-nops.ll
+++ b/llvm/test/MC/X86/stackmap-nops.ll
@@ -41,6 +41,7 @@
tail call void (i64, i32, ...)* @llvm.experimental.stackmap(i64 13, i32 13)
tail call void (i64, i32, ...)* @llvm.experimental.stackmap(i64 14, i32 14)
tail call void (i64, i32, ...)* @llvm.experimental.stackmap(i64 15, i32 15)
+ tail call void (i64, i32, ...)* @llvm.experimental.stackmap(i64 16, i32 0)
ret void
}