[PATCH] D82602: [SelectionDAG] don't split branch on logic-of-vector-compares

[Sanjay Patel via Phabricator via llvm-commits]

spatel updated this revision to Diff 274565.
spatel added a comment.

Patch updated:
Rebased after rGe9c6b63d4a16c795 <https://reviews.llvm.org/rGe9c6b63d4a16c7955bf0e7d5c1ab4adbb9d385cc> - this patch doesn't affect any SystemZ tests now (thanks!).


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D82602/new/

https://reviews.llvm.org/D82602

Files:
  llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  llvm/test/CodeGen/AArch64/vec-extract-branch.ll
  llvm/test/CodeGen/X86/setcc-logic.ll


Index: llvm/test/CodeGen/X86/setcc-logic.ll
===================================================================
--- llvm/test/CodeGen/X86/setcc-logic.ll
+++ llvm/test/CodeGen/X86/setcc-logic.ll
@@ -323,15 +323,12 @@
 ; CHECK-NEXT:    xorpd %xmm1, %xmm1
 ; CHECK-NEXT:    cmpltpd %xmm0, %xmm1
 ; CHECK-NEXT:    movmskpd %xmm1, %eax
-; CHECK-NEXT:    testb $1, %al
-; CHECK-NEXT:    je .LBB16_3
-; CHECK-NEXT:  # %bb.1:
-; CHECK-NEXT:    shrb %al
-; CHECK-NEXT:    je .LBB16_3
-; CHECK-NEXT:  # %bb.2: # %true
+; CHECK-NEXT:    cmpb $3, %al
+; CHECK-NEXT:    jne .LBB16_2
+; CHECK-NEXT:  # %bb.1: # %true
 ; CHECK-NEXT:    movl $42, %eax
 ; CHECK-NEXT:    retq
-; CHECK-NEXT:  .LBB16_3: # %false
+; CHECK-NEXT:  .LBB16_2: # %false
 ; CHECK-NEXT:    movl $88, %eax
 ; CHECK-NEXT:    retq
   %t1 = fcmp ogt <2 x double> %x, zeroinitializer
Index: llvm/test/CodeGen/AArch64/vec-extract-branch.ll
===================================================================
--- llvm/test/CodeGen/AArch64/vec-extract-branch.ll
+++ llvm/test/CodeGen/AArch64/vec-extract-branch.ll
@@ -6,16 +6,15 @@
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    fcmgt v0.2d, v0.2d, #0.0
 ; CHECK-NEXT:    xtn v0.2s, v0.2d
-; CHECK-NEXT:    fmov w8, s0
-; CHECK-NEXT:    tbz w8, #0, .LBB0_3
-; CHECK-NEXT:  // %bb.1:
 ; CHECK-NEXT:    mov w8, v0.s[1]
-; CHECK-NEXT:    tbz w8, #0, .LBB0_3
-; CHECK-NEXT:  // %bb.2: // %true
+; CHECK-NEXT:    fmov w9, s0
+; CHECK-NEXT:    and w8, w9, w8
+; CHECK-NEXT:    tbz w8, #0, .LBB0_2
+; CHECK-NEXT:  // %bb.1: // %true
 ; CHECK-NEXT:    mov w8, #42
 ; CHECK-NEXT:    sdiv w0, w8, w0
 ; CHECK-NEXT:    ret
-; CHECK-NEXT:  .LBB0_3: // %false
+; CHECK-NEXT:  .LBB0_2: // %false
 ; CHECK-NEXT:    mov w0, #88
 ; CHECK-NEXT:    ret
   %t1 = fcmp ogt <2 x double> %x, zeroinitializer
Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2296,7 +2296,9 @@
 
   // If this is a series of conditions that are or'd or and'd together, emit
   // this as a sequence of branches instead of setcc's with and/or operations.
-  // As long as jumps are not expensive, this should improve performance.
+  // As long as jumps are not expensive (exceptions for multi-use logic ops,
+  // unpredictable branches, and vector extracts because those jumps are likely
+  // expensive for any target), this should improve performance.
   // For example, instead of something like:
   //     cmp A, B
   //     C = seteq
@@ -2311,9 +2313,12 @@
   //     jle foo
   if (const BinaryOperator *BOp = dyn_cast<BinaryOperator>(CondVal)) {
     Instruction::BinaryOps Opcode = BOp->getOpcode();
+    Value *Vec, *BOp0 = BOp->getOperand(0), *BOp1 = BOp->getOperand(1);
     if (!DAG.getTargetLoweringInfo().isJumpExpensive() && BOp->hasOneUse() &&
         !I.hasMetadata(LLVMContext::MD_unpredictable) &&
-        (Opcode == Instruction::And || Opcode == Instruction::Or)) {
+        (Opcode == Instruction::And || Opcode == Instruction::Or) &&
+        !(match(BOp0, m_ExtractElt(m_Value(Vec), m_Value())) &&
+          match(BOp1, m_ExtractElt(m_Specific(Vec), m_Value())))) {
       FindMergedConditions(BOp, Succ0MBB, Succ1MBB, BrMBB, BrMBB,
                            Opcode,
                            getEdgeProbability(BrMBB, Succ0MBB),


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