[llvm] d7600c7 - [DAG] select Cond, C, -1 --> or (sext (not Cond)), C when C is MVT::i1

[Amaury Séchet via llvm-commits]

Author: Amaury Séchet
Date: 2022-09-30T00:36:58Z
New Revision: d7600c7ccb475dd57bbb857872455435d72fd280

URL: https://github.com/llvm/llvm-project/commit/d7600c7ccb475dd57bbb857872455435d72fd280
DIFF: https://github.com/llvm/llvm-project/commit/d7600c7ccb475dd57bbb857872455435d72fd280.diff

LOG: [DAG] select Cond, C, -1 --> or (sext (not Cond)), C when C is MVT::i1

In the spirit of D130765 . Get rid of cbranches and/or cmov. Usually shorter, but sometime not, becaus eit's hard to prededict when dependency breaking xor will be introduced.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D134736

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/test/CodeGen/X86/pr16031.ll
    llvm/test/CodeGen/X86/select_const.ll
    llvm/test/CodeGen/X86/zext-sext.ll

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 0f8f0da40bef9..8d428dccf8655 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10341,6 +10341,13 @@ SDValue DAGCombiner::foldSelectOfConstants(SDNode *N) {
         return DAG.getNode(ISD::OR, DL, VT, Cond, N2);
       }
 
+      // select Cond, C, -1 --> or (sext (not Cond)), C
+      if (C2->isAllOnes()) {
+        SDValue NotCond = DAG.getNOT(DL, Cond, MVT::i1);
+        NotCond = DAG.getSExtOrTrunc(NotCond, DL, VT);
+        return DAG.getNode(ISD::OR, DL, VT, NotCond, N1);
+      }
+
       if (SDValue V = foldSelectOfConstantsUsingSra(N, DAG))
         return V;
     }

diff  --git a/llvm/test/CodeGen/X86/pr16031.ll b/llvm/test/CodeGen/X86/pr16031.ll
index 3aeaec1b9ce77..db007837e839b 100644
--- a/llvm/test/CodeGen/X86/pr16031.ll
+++ b/llvm/test/CodeGen/X86/pr16031.ll
@@ -4,10 +4,10 @@
 define i64 @main(i1 %tobool1) nounwind {
 ; CHECK-LABEL: main:
 ; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    testb $1, {{[0-9]+}}(%esp)
-; CHECK-NEXT:    movl $-12, %ecx
-; CHECK-NEXT:    movl $-1, %eax
-; CHECK-NEXT:    cmovnel %ecx, %eax
+; CHECK-NEXT:    movzbl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    andl $1, %eax
+; CHECK-NEXT:    decl %eax
+; CHECK-NEXT:    orl $-12, %eax
 ; CHECK-NEXT:    xorl %ecx, %ecx
 ; CHECK-NEXT:    movl %eax, %edx
 ; CHECK-NEXT:    addl $-1, %edx

diff  --git a/llvm/test/CodeGen/X86/select_const.ll b/llvm/test/CodeGen/X86/select_const.ll
index c910e3da33ed7..14827f14c158c 100644
--- a/llvm/test/CodeGen/X86/select_const.ll
+++ b/llvm/test/CodeGen/X86/select_const.ll
@@ -268,9 +268,9 @@ define i8 @sel_1_neg1(i32 %x) {
 ; CHECK-LABEL: sel_1_neg1:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    cmpl $43, %edi
-; CHECK-NEXT:    setge %al
-; CHECK-NEXT:    shlb $2, %al
-; CHECK-NEXT:    decb %al
+; CHECK-NEXT:    setl %al
+; CHECK-NEXT:    negb %al
+; CHECK-NEXT:    orb $3, %al
 ; CHECK-NEXT:    retq
   %cmp = icmp sgt i32 %x, 42
   %sel = select i1 %cmp, i8 3, i8 -1
@@ -432,10 +432,9 @@ define i32 @select_C1_C2_signext(i1 signext %cond) {
 define i32 @select_n_or_minus1(i1 signext %cond) {
 ; CHECK-LABEL: select_n_or_minus1:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    testb $1, %dil
-; CHECK-NEXT:    movl $12414, %ecx # imm = 0x307E
-; CHECK-NEXT:    movl $-1, %eax
-; CHECK-NEXT:    cmovnel %ecx, %eax
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    notl %eax
+; CHECK-NEXT:    orl $12414, %eax # imm = 0x307E
 ; CHECK-NEXT:    retq
   %sel = select i1 %cond, i32 12414, i32 -1
   ret i32 %sel

diff  --git a/llvm/test/CodeGen/X86/zext-sext.ll b/llvm/test/CodeGen/X86/zext-sext.ll
index 929ba0b1c18ef..5140587ef2775 100644
--- a/llvm/test/CodeGen/X86/zext-sext.ll
+++ b/llvm/test/CodeGen/X86/zext-sext.ll
@@ -16,26 +16,26 @@ define void @func(ptr %a, ptr %b, ptr %c, ptr %d) nounwind {
 ; CHECK-NEXT:    movq (%rdx), %rax
 ; CHECK-NEXT:    movswl 8(%rdi), %edx
 ; CHECK-NEXT:    movswl (%rax,%rsi,2), %eax
-; CHECK-NEXT:    movl $1, %esi
 ; CHECK-NEXT:    imull %edx, %eax
-; CHECK-NEXT:    xorl %edx, %edx
 ; CHECK-NEXT:    addl $2138875574, %eax # imm = 0x7F7CA6B6
-; CHECK-NEXT:    cmpl $-8608074, %eax # imm = 0xFF7CA6B6
-; CHECK-NEXT:    movslq %eax, %rdi
-; CHECK-NEXT:    setl %dl
 ; CHECK-NEXT:    cmpl $2138875574, %eax # imm = 0x7F7CA6B6
-; CHECK-NEXT:    movq %rdi, %r8
-; CHECK-NEXT:    leal -1(%rdx,%rdx), %edx
-; CHECK-NEXT:    cmovll %edx, %esi
-; CHECK-NEXT:    subq %rax, %r8
+; CHECK-NEXT:    setl %sil
+; CHECK-NEXT:    cmpl $-8608074, %eax # imm = 0xFF7CA6B6
+; CHECK-NEXT:    setge %dl
+; CHECK-NEXT:    andb %sil, %dl
+; CHECK-NEXT:    movslq %eax, %rsi
+; CHECK-NEXT:    movzbl %dl, %edx
+; CHECK-NEXT:    movq %rsi, %rdi
+; CHECK-NEXT:    subq %rax, %rdi
+; CHECK-NEXT:    negl %edx
 ; CHECK-NEXT:    xorl %eax, %eax
-; CHECK-NEXT:    cmpl $1, %esi
-; CHECK-NEXT:    cmovneq %rax, %r8
-; CHECK-NEXT:    testl %edi, %edi
-; CHECK-NEXT:    cmovnsq %rax, %r8
+; CHECK-NEXT:    testl $-2, %edx
+; CHECK-NEXT:    cmovneq %rax, %rdi
+; CHECK-NEXT:    testl %esi, %esi
+; CHECK-NEXT:    cmovnsq %rax, %rdi
 ; CHECK-NEXT:    movq (%rcx), %rax
-; CHECK-NEXT:    subq %r8, %rdi
-; CHECK-NEXT:    leaq -2138875574(%rax,%rdi), %rax
+; CHECK-NEXT:    subq %rdi, %rsi
+; CHECK-NEXT:    leaq -2138875574(%rax,%rsi), %rax
 ; CHECK-NEXT:    movq %rax, (%rcx)
 ; CHECK-NEXT:    retq
 entry: