In the pre-RA scheduler, maintain cmp+br proximity.

This is done by pushing physical register definitions close to their
use, which happens to handle flag definitions if they're not glued to
the branch. This seems to be generally a good thing though, so I
didn't need to add a target hook yet.

The primary motivation is to generate code closer to what people
expect and rule out missed opportunity from enabling macro-op
fusion. As a side benefit, we get several 2-5% gains on x86
benchmarks. There is one regression:
SingleSource/Benchmarks/Shootout/lists slows down be -10%. But this is
an independent scheduler bug that will be tracked separately.
See rdar://problem/9283108.

Incidentally, pre-RA scheduling is only half the solution. Fixing the
later passes is tracked by:
<rdar://problem/8932804> [pre-RA-sched] on x86, attempt to schedule CMP/TEST adjacent with condition jump

Fixes:
<rdar://problem/9262453> Scheduler unnecessary break of cmp/jump fusion


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129508 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 65 insertions, 0 deletions

diff --git a/test/CodeGen/X86/2011-04-13-SchedCmpJmp.ll b/test/CodeGen/X86/2011-04-13-SchedCmpJmp.ll
new file mode 100644
index 0000000000..07b1971218
--- /dev/null
+++ b/test/CodeGen/X86/2011-04-13-SchedCmpJmp.ll
@@ -0,0 +1,65 @@
+; RUN: llc < %s -mtriple=x86_64-apple-darwin -mcpu=yonah | FileCheck %s
+; Reduced from JavaScriptCore
+
+%"class.JSC::CodeLocationCall" = type { [8 x i8] }
+%"class.JSC::JSGlobalData" = type { [4 x i8] }
+%"class.JSC::FunctionPtr" = type { i8* }
+%"class.JSC::Structure" = type { [4 x i8] }
+%"class.JSC::UString" = type { i8* }
+%"class.JSC::JSString" = type { [16 x i8], i32, %"class.JSC::UString", i32 }
+
+declare hidden fastcc void @_ZN3JSCL23returnToThrowTrampolineEPNS_12JSGlobalDataENS_16ReturnAddressPtrERS2_(%"class.JSC::JSGlobalData"* nocapture, i8*, %"class.JSC::FunctionPtr"* nocapture) nounwind noinline ssp
+
+; Avoid hoisting the test above loads or copies
+; CHECK: %entry
+; CHECK: cmpq
+; CHECK-NOT: mov
+; CHECK: jb
+define i32 @cti_op_eq(i8** nocapture %args) nounwind ssp {
+entry:
+  %0 = load i8** null, align 8
+  %tmp13 = bitcast i8* %0 to %"class.JSC::CodeLocationCall"*
+  %tobool.i.i.i = icmp ugt i8* undef, inttoptr (i64 281474976710655 to i8*)
+  %or.cond.i = and i1 %tobool.i.i.i, undef
+  br i1 %or.cond.i, label %if.then.i, label %if.end.i
+
+if.then.i:                                        ; preds = %entry
+  br i1 undef, label %if.then.i.i.i, label %_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit
+
+if.then.i.i.i:                                    ; preds = %if.then.i
+  %conv.i.i.i.i = trunc i64 undef to i32
+  br label %_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit
+
+if.end.i:                                         ; preds = %entry
+  br i1 undef, label %land.rhs.i121.i, label %_ZNK3JSC7JSValue8isStringEv.exit122.i
+
+land.rhs.i121.i:                                  ; preds = %if.end.i
+  %tmp.i.i117.i = load %"class.JSC::Structure"** undef, align 8
+  br label %_ZNK3JSC7JSValue8isStringEv.exit122.i
+
+_ZNK3JSC7JSValue8isStringEv.exit122.i:            ; preds = %land.rhs.i121.i, %if.end.i
+  %brmerge.i = or i1 undef, false
+  %or.cond = or i1 false, %brmerge.i
+  br i1 %or.cond, label %_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit, label %if.then.i92.i
+
+if.then.i92.i:                                    ; preds = %_ZNK3JSC7JSValue8isStringEv.exit122.i
+  tail call void @_ZNK3JSC8JSString11resolveRopeEPNS_9ExecStateE(%"class.JSC::JSString"* undef, %"class.JSC::CodeLocationCall"* %tmp13) nounwind
+  unreachable
+
+_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit: ; preds = %_ZNK3JSC7JSValue8isStringEv.exit122.i, %if.then.i.i.i, %if.then.i
+
+  %1 = load i8** undef, align 8
+  br i1 undef, label %do.end39, label %do.body27
+
+do.body27:                                        ; preds = %_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit
+  %tmp30 = bitcast i8* %1 to %"class.JSC::JSGlobalData"*
+  %2 = getelementptr inbounds i8** %args, i64 -1
+  %3 = bitcast i8** %2 to %"class.JSC::FunctionPtr"*
+  tail call fastcc void @_ZN3JSCL23returnToThrowTrampolineEPNS_12JSGlobalDataENS_16ReturnAddressPtrERS2_(%"class.JSC::JSGlobalData"* %tmp30, i8* undef, %"class.JSC::FunctionPtr"* %3)
+  unreachable
+
+do.end39:                                         ; preds = %_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit
+  ret i32 undef
+}
+
+declare void @_ZNK3JSC8JSString11resolveRopeEPNS_9ExecStateE(%"class.JSC::JSString"*, %"class.JSC::CodeLocationCall"*)