[PowerPC] Mark jumps as expensive (using using CR bits)
On PowerPC, which has a full set of logical operations on (its multiple sets
of) condition-register bits, it is not profitable to break of complex
conditions feeding a jump into multiple jumps. We can turn off this feature of
CGP/SDAGBuilder by marking jumps as "expensive".
P7 test-suite speedups (no regressions):
MultiSource/Benchmarks/FreeBench/pcompress2/pcompress2
-0.626647% +/- 0.323583%
MultiSource/Benchmarks/Olden/power/power
-18.2821% +/- 8.06481%
llvm-svn: 228895
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 7ecfac6..15a0818 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -687,8 +687,10 @@
// With 32 condition bits, we don't need to sink (and duplicate) compares
// aggressively in CodeGenPrep.
- if (Subtarget.useCRBits())
+ if (Subtarget.useCRBits()) {
setHasMultipleConditionRegisters();
+ setJumpIsExpensive();
+ }
setMinFunctionAlignment(2);
if (Subtarget.isDarwin())
diff --git a/llvm/test/CodeGen/PowerPC/no-pref-jumps.ll b/llvm/test/CodeGen/PowerPC/no-pref-jumps.ll
new file mode 100644
index 0000000..d9490f1
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/no-pref-jumps.ll
@@ -0,0 +1,36 @@
+; RUN: llc -mcpu=pwr7 < %s | FileCheck %s
+target datalayout = "E-m:e-i64:64-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+; Function Attrs: nounwind
+define void @foo(i32 signext %a, i32 signext %b) #0 {
+entry:
+ %cmp = icmp sgt i32 %a, 5
+ %cmp1 = icmp slt i32 %b, 3
+ %or.cond = or i1 %cmp, %cmp1
+ br i1 %or.cond, label %if.then, label %if.else
+
+; CHECK-LABEL: @foo
+; CHECK: cmpwi
+; CHECK: cmpwi
+; CHECK: cror
+; CHECK: blr
+
+if.then: ; preds = %entry
+ tail call void bitcast (void (...)* @bar to void ()*)() #0
+ br label %if.end
+
+if.else: ; preds = %entry
+ tail call void bitcast (void (...)* @car to void ()*)() #0
+ br label %if.end
+
+if.end: ; preds = %if.else, %if.then
+ ret void
+}
+
+declare void @bar(...)
+
+declare void @car(...)
+
+attributes #0 = { nounwind }
+