[PATCH] D59633: [PowerPC] Look through copies for compare elimination
Nemanja Ivanovic via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 28 20:06:44 PDT 2019
nemanjai updated this revision to Diff 192771.
nemanjai added a comment.
Updated to not look through copies if that leads to a physical register since that will never produce a defining MI.
Repository:
rL LLVM
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D59633/new/
https://reviews.llvm.org/D59633
Files:
lib/Target/PowerPC/PPCInstrInfo.cpp
test/CodeGen/PowerPC/eliminate-compare-of-copy.ll
Index: test/CodeGen/PowerPC/eliminate-compare-of-copy.ll
===================================================================
--- test/CodeGen/PowerPC/eliminate-compare-of-copy.ll
+++ test/CodeGen/PowerPC/eliminate-compare-of-copy.ll
@@ -0,0 +1,28 @@
+; RUN: llc -verify-machineinstrs -mtriple=powerpc64le-unknown-linux-gnu \
+; RUN: -mcpu=pwr8 -ppc-asm-full-reg-names < %s | FileCheck %s
+
+define dso_local signext i32 @func(i32 zeroext %x, i32 zeroext %y) local_unnamed_addr #0 {
+; CHECK-LABEL: func
+; CHECK: or. {{r[0-9]+}}, r4, r3
+; CHECK-NOT: cmplwi
+entry:
+ %or = or i32 %y, %x
+ %tobool = icmp eq i32 %or, 0
+ br i1 %tobool, label %if.else, label %if.then
+
+if.then: ; preds = %entry
+ %call = tail call signext i32 bitcast (i32 (...)* @f1 to i32 ()*)() #2
+ br label %return
+
+if.else: ; preds = %entry
+ %call1 = tail call signext i32 bitcast (i32 (...)* @f2 to i32 ()*)() #2
+ br label %return
+
+return: ; preds = %if.else, %if.then
+ %retval.0 = phi i32 [ %call, %if.then ], [ %call1, %if.else ]
+ ret i32 %retval.0
+}
+
+declare signext i32 @f1(...) local_unnamed_addr #1
+
+declare signext i32 @f2(...) local_unnamed_addr #1
Index: lib/Target/PowerPC/PPCInstrInfo.cpp
===================================================================
--- lib/Target/PowerPC/PPCInstrInfo.cpp
+++ lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -1651,6 +1651,7 @@
if (OpC == PPC::FCMPUS || OpC == PPC::FCMPUD)
return false;
+ const TargetRegisterInfo *TRI = &getRegisterInfo();
// The record forms set the condition register based on a signed comparison
// with zero (so says the ISA manual). This is not as straightforward as it
// seems, however, because this is always a 64-bit comparison on PPC64, even
@@ -1664,6 +1665,11 @@
bool is32BitUnsignedCompare = OpC == PPC::CMPLWI || OpC == PPC::CMPLW;
bool is64BitUnsignedCompare = OpC == PPC::CMPLDI || OpC == PPC::CMPLD;
+ // Look through copies unless that gets us to a physical register.
+ unsigned ActualSrc = TRI->lookThruCopyLike(SrcReg, MRI);
+ if (TargetRegisterInfo::isVirtualRegister(ActualSrc))
+ SrcReg = ActualSrc;
+
// Get the unique definition of SrcReg.
MachineInstr *MI = MRI->getUniqueVRegDef(SrcReg);
if (!MI) return false;
@@ -1792,7 +1798,6 @@
}
// Search for Sub.
- const TargetRegisterInfo *TRI = &getRegisterInfo();
--I;
// Get ready to iterate backward from CmpInstr.
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