[llvm] 861f5dd - [X86][NFC] Minor improvement in X86InstrInfo::optimizeCompareInstr

[Shengchen Kan via llvm-commits]

Author: Shengchen Kan
Date: 2022-11-21T21:00:07+08:00
New Revision: 861f5dd688c19d206cc44718be9ff75894065d46

URL: https://github.com/llvm/llvm-project/commit/861f5dd688c19d206cc44718be9ff75894065d46
DIFF: https://github.com/llvm/llvm-project/commit/861f5dd688c19d206cc44718be9ff75894065d46.diff

LOG: [X86][NFC] Minor improvement in X86InstrInfo::optimizeCompareInstr

Before this patch, the code enumerated `getCondFromBranch`, `getCondFromSETCC` and `getCondFromFromCMov` to get the condition code of a `MachineInstr`, and assigned the result to variable `OldCC` when `MI || IsSwapped || ImmDelta != 0` was satisfiled.

After this patch, the `if-else` structure is eliminated by using `getCondFromMI`. Since `OldCC` is only used when  `MI || IsSwapped || ImmDelta != 0`  is true, it is initialized with `getCondFromMI` directly outside the scope of `if` now.

Reviewed By: pengfei

Differential Revision: https://reviews.llvm.org/D138349

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86InstrInfo.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 86dc8f92aa4d2..ea34f45173ce9 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -4498,18 +4498,10 @@ bool X86InstrInfo::optimizeCompareInstr(MachineInstr &CmpInstr, Register SrcReg,
       continue;
 
     // EFLAGS is used by this instruction.
-    X86::CondCode OldCC = X86::COND_INVALID;
-    if (MI || IsSwapped || ImmDelta != 0) {
-      // We decode the condition code from opcode.
-      if (Instr.isBranch())
-        OldCC = X86::getCondFromBranch(Instr);
-      else {
-        OldCC = X86::getCondFromSETCC(Instr);
-        if (OldCC == X86::COND_INVALID)
-          OldCC = X86::getCondFromCMov(Instr);
-      }
-      if (OldCC == X86::COND_INVALID) return false;
-    }
+    X86::CondCode OldCC = X86::getCondFromMI(Instr);
+    if ((MI || IsSwapped || ImmDelta != 0) && OldCC == X86::COND_INVALID)
+      return false;
+
     X86::CondCode ReplacementCC = X86::COND_INVALID;
     if (MI) {
       switch (OldCC) {