[PowerPC] Put the CR field in low bits of GRC during copying CRRC to GRC.

Summary: How we copying the CRRC to GRC is using a single MFOCRF to copy the contents of CR field n (CR bits 4×n+32:4×n+35) into bits 4×n+32:4×n+35 of register GRC. That’s not correct because we expect the value of destination register equals to source so we have to put the the contents of CR field in the lowest 4 bits. This patch adds a RLWINM after MFOCRF to achieve that.
The problem came up when adding builtins for xvtdivdp, xvtdivsp, xvtsqrtdp, xvtsqrtsp, as posted in D88278. We need to move the outputs (in CR register) to GRC. However outputs of these instructions may not in a fixed CR# register, so we can’t directly add a rotation instruction in the .td patterns, but need to wait until the CR register is determined. Then we confirmed this should be a bug in POST-RA PSEUDO PASS.

Reviewed By: nemanjai, shchenz

Differential Revision: https://reviews.llvm.org/D88274

Author: Esme-Yi

llvm/lib/Target/PowerPC/PPCInstrHTM.td

@@ -164,9 +164,8 @@ def : Pat<(int_ppc_tsuspend),
           (TSR 0)>;
 
 def : Pat<(i64 (int_ppc_ttest)),
-          (RLDICL (i64 (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
-                                      (TABORTWCI 0, (LI 0), 0), sub_32)),
-                   36, 28)>;
+          (i64 (INSERT_SUBREG
+                (i64 (IMPLICIT_DEF)), (TABORTWCI 0, (LI 0), 0), sub_32))>;
 
 } // [HasHTM]
 

llvm/lib/Target/PowerPC/PPCInstrInfo.cpp

@@ -1272,14 +1272,22 @@ void PPCInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
        .addImm(31);
     return;
   } else if (PPC::CRRCRegClass.contains(SrcReg) &&
-      PPC::G8RCRegClass.contains(DestReg)) {
-    BuildMI(MBB, I, DL, get(PPC::MFOCRF8), DestReg).addReg(SrcReg);
-    getKillRegState(KillSrc);
-    return;
-  } else if (PPC::CRRCRegClass.contains(SrcReg) &&
-      PPC::GPRCRegClass.contains(DestReg)) {
-    BuildMI(MBB, I, DL, get(PPC::MFOCRF), DestReg).addReg(SrcReg);
+             (PPC::G8RCRegClass.contains(DestReg) ||
+              PPC::GPRCRegClass.contains(DestReg))) {
+    bool Is64Bit = PPC::G8RCRegClass.contains(DestReg);
+    unsigned MvCode = Is64Bit ? PPC::MFOCRF8 : PPC::MFOCRF;
+    unsigned ShCode = Is64Bit ? PPC::RLWINM8 : PPC::RLWINM;
+    unsigned CRNum = TRI->getEncodingValue(SrcReg);
+    BuildMI(MBB, I, DL, get(MvCode), DestReg).addReg(SrcReg);
     getKillRegState(KillSrc);
+    if (CRNum == 7)
+      return;
+    // Shift the CR bits to make the CR field in the lowest 4 bits of GRC.
+    BuildMI(MBB, I, DL, get(ShCode), DestReg)
+        .addReg(DestReg, RegState::Kill)
+        .addImm(CRNum * 4 + 4)
+        .addImm(28)
+        .addImm(31);
     return;
   } else if (PPC::G8RCRegClass.contains(SrcReg) &&
              PPC::VSFRCRegClass.contains(DestReg)) {

llvm/test/CodeGen/PowerPC/htm-ttest.ll

@@ -8,7 +8,7 @@ define dso_local void @main() #0 {
 ; CHECK-NEXT:    li 3, 0
 ; CHECK-NEXT:    tabortwci. 0, 3, 0
 ; CHECK-NEXT:    mfocrf 3, 128
-; CHECK-NEXT:    rldicl 3, 3, 36, 28
+; CHECK-NEXT:    srwi 3, 3, 28
 ; CHECK-NEXT:    rlwinm. 3, 3, 31, 30, 31
 ; CHECK-NEXT:    beqlr+ 0
 ; CHECK-NEXT:  # %bb.1: