[PowerPC] Use 16-byte alignment for modern cores for functions/loops
Most modern PowerPC cores prefer that functions and loops start on
16-byte-aligned boundaries (*), so instruct block placement, etc. to make this
happen. The branch selector has also been adjusted so account for the extra
nops that might now be inserted before loop headers.
(*) Some cores actually prefer other alignments for small loops, but that will
be addressed in a follow-up commit.
llvm-svn: 225115
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 32f958e..8d8c322 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -679,6 +679,24 @@
if (Subtarget.isDarwin())
setPrefFunctionAlignment(4);
+ switch (Subtarget.getDarwinDirective()) {
+ default: break;
+ case PPC::DIR_970:
+ case PPC::DIR_A2:
+ case PPC::DIR_E500mc:
+ case PPC::DIR_E5500:
+ case PPC::DIR_PWR4:
+ case PPC::DIR_PWR5:
+ case PPC::DIR_PWR5X:
+ case PPC::DIR_PWR6:
+ case PPC::DIR_PWR6X:
+ case PPC::DIR_PWR7:
+ case PPC::DIR_PWR8:
+ setPrefFunctionAlignment(4);
+ setPrefLoopAlignment(4);
+ break;
+ }
+
setInsertFencesForAtomic(true);
if (Subtarget.enableMachineScheduler())
@@ -688,8 +706,8 @@
computeRegisterProperties();
- // The Freescale cores does better with aggressive inlining of memcpy and
- // friends. Gcc uses same threshold of 128 bytes (= 32 word stores).
+ // The Freescale cores do better with aggressive inlining of memcpy and
+ // friends. GCC uses same threshold of 128 bytes (= 32 word stores).
if (Subtarget.getDarwinDirective() == PPC::DIR_E500mc ||
Subtarget.getDarwinDirective() == PPC::DIR_E5500) {
MaxStoresPerMemset = 32;
@@ -698,8 +716,6 @@
MaxStoresPerMemcpyOptSize = 8;
MaxStoresPerMemmove = 32;
MaxStoresPerMemmoveOptSize = 8;
-
- setPrefFunctionAlignment(4);
}
}