[llvm] be95b4d - [PowerPC] Look through OR, AND, XOR instructions when checking a clear.

[Stefan Pintilie via llvm-commits]

Author: Stefan Pintilie
Date: 2023-05-08T14:25:20-04:00
New Revision: be95b4dec2604247d9fbad5f7641b4373b740904

URL: https://github.com/llvm/llvm-project/commit/be95b4dec2604247d9fbad5f7641b4373b740904
DIFF: https://github.com/llvm/llvm-project/commit/be95b4dec2604247d9fbad5f7641b4373b740904.diff

LOG: [PowerPC] Look through OR, AND, XOR instructions when checking a clear.

This patch adds the additional step of looking through AND, OR, XOR
instructions when we check the number of leading zeros.

Reviewed By: shchenz

Differential Revision: https://reviews.llvm.org/D149223

Added: 
    

Modified: 
    llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
    llvm/test/CodeGen/PowerPC/ppc-clear-before-return.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp b/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
index f1d1d2f3757f6..34da55e40c728 100644
--- a/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
+++ b/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
@@ -219,6 +219,20 @@ static unsigned getKnownLeadingZeroCount(const unsigned Reg,
       Opcode == PPC::LBZU8 || Opcode == PPC::LBZUX8)
     return 56;
 
+  if (Opcode == PPC::AND || Opcode == PPC::AND8 || Opcode == PPC::AND_rec ||
+      Opcode == PPC::AND8_rec)
+    return std::max(
+        getKnownLeadingZeroCount(MI->getOperand(1).getReg(), TII, MRI),
+        getKnownLeadingZeroCount(MI->getOperand(2).getReg(), TII, MRI));
+
+  if (Opcode == PPC::OR || Opcode == PPC::OR8 || Opcode == PPC::XOR ||
+      Opcode == PPC::XOR8 || Opcode == PPC::OR_rec ||
+      Opcode == PPC::OR8_rec || Opcode == PPC::XOR_rec ||
+      Opcode == PPC::XOR8_rec)
+    return std::min(
+        getKnownLeadingZeroCount(MI->getOperand(1).getReg(), TII, MRI),
+        getKnownLeadingZeroCount(MI->getOperand(2).getReg(), TII, MRI));
+
   if (TII->isZeroExtended(Reg, MRI))
     return 32;
 

diff  --git a/llvm/test/CodeGen/PowerPC/ppc-clear-before-return.ll b/llvm/test/CodeGen/PowerPC/ppc-clear-before-return.ll
index 03d859f7abb4b..f77bd692cc7f0 100644
--- a/llvm/test/CodeGen/PowerPC/ppc-clear-before-return.ll
+++ b/llvm/test/CodeGen/PowerPC/ppc-clear-before-return.ll
@@ -15,7 +15,6 @@ define dso_local i64 @test_xor(ptr nocapture noundef readonly %inp) local_unname
 ; 64BIT-NEXT:    lbz r4, 0(r3)
 ; 64BIT-NEXT:    lbz r3, 1(r3)
 ; 64BIT-NEXT:    xor r3, r3, r4
-; 64BIT-NEXT:    clrldi r3, r3, 56
 ; 64BIT-NEXT:    blr
 ;
 ; 32BIT-LABEL: test_xor:
@@ -43,7 +42,6 @@ define dso_local i64 @test_xor2(ptr nocapture noundef readonly %inp) local_unnam
 ; 64BIT-NEXT:    lbz r3, 2(r3)
 ; 64BIT-NEXT:    xor r4, r5, r4
 ; 64BIT-NEXT:    xor r3, r4, r3
-; 64BIT-NEXT:    clrldi r3, r3, 56
 ; 64BIT-NEXT:    blr
 ;
 ; 32BIT-LABEL: test_xor2:
@@ -74,7 +72,6 @@ define dso_local i64 @test_or(ptr nocapture noundef readonly %inp) local_unnamed
 ; 64BIT-NEXT:    lbz r4, 0(r3)
 ; 64BIT-NEXT:    lbz r3, 1(r3)
 ; 64BIT-NEXT:    or r3, r3, r4
-; 64BIT-NEXT:    clrldi r3, r3, 56
 ; 64BIT-NEXT:    blr
 ;
 ; 32BIT-LABEL: test_or:
@@ -102,7 +99,6 @@ define dso_local i64 @test_or2(ptr nocapture noundef readonly %inp) local_unname
 ; 64BIT-NEXT:    lbz r3, 2(r3)
 ; 64BIT-NEXT:    or r4, r5, r4
 ; 64BIT-NEXT:    or r3, r4, r3
-; 64BIT-NEXT:    clrldi r3, r3, 56
 ; 64BIT-NEXT:    blr
 ;
 ; 32BIT-LABEL: test_or2:
@@ -133,7 +129,6 @@ define dso_local i64 @test_and(ptr nocapture noundef readonly %inp) local_unname
 ; 64BIT-NEXT:    lbz r4, 0(r3)
 ; 64BIT-NEXT:    lbz r3, 1(r3)
 ; 64BIT-NEXT:    and r3, r3, r4
-; 64BIT-NEXT:    clrldi r3, r3, 56
 ; 64BIT-NEXT:    blr
 ;
 ; 32BIT-LABEL: test_and:
@@ -161,7 +156,6 @@ define dso_local i64 @test_and2(ptr nocapture noundef readonly %inp) local_unnam
 ; 64BIT-NEXT:    lbz r3, 2(r3)
 ; 64BIT-NEXT:    and r4, r5, r4
 ; 64BIT-NEXT:    and r3, r4, r3
-; 64BIT-NEXT:    clrldi r3, r3, 56
 ; 64BIT-NEXT:    blr
 ;
 ; 32BIT-LABEL: test_and2:
@@ -196,7 +190,6 @@ define dso_local i64 @test_mixed(ptr nocapture noundef readonly %inp) local_unna
 ; 64BIT-NEXT:    and r4, r5, r4
 ; 64BIT-NEXT:    xor r4, r4, r6
 ; 64BIT-NEXT:    or r3, r4, r3
-; 64BIT-NEXT:    clrldi r3, r3, 56
 ; 64BIT-NEXT:    blr
 ;
 ; 32BIT-LABEL: test_mixed:
@@ -236,7 +229,6 @@ define dso_local i64 @test_mixedtype(ptr nocapture noundef readonly %inp, ptr no
 ; 64BIT-NEXT:    and r5, r6, r5
 ; 64BIT-NEXT:    xor r3, r5, r3
 ; 64BIT-NEXT:    or r3, r3, r4
-; 64BIT-NEXT:    clrldi r3, r3, 48
 ; 64BIT-NEXT:    blr
 ;
 ; 32BIT-LABEL: test_mixedtype: