[llvm] [Sparc] Optimize compare instruction (PR #167140)

[Sergei Barannikov via llvm-commits]

================
@@ -0,0 +1,248 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=sparc | FileCheck %s
+; RUN: llc < %s -mtriple=sparcv9 | FileCheck %s -check-prefix=CHECK64
+
+define i32 @test(i32 %a) nounwind {
+; CHECK-LABEL: test:
+; CHECK:       ! %bb.0: ! %entry
+; CHECK-NEXT:    andcc %o0, 1, %g0
+; CHECK-NEXT:    bne .LBB0_2
+; CHECK-NEXT:    nop
+; CHECK-NEXT:  ! %bb.1: ! %if.end
+; CHECK-NEXT:    retl
+; CHECK-NEXT:    mov 2, %o0
+; CHECK-NEXT:  .LBB0_2: ! %if.then
+; CHECK-NEXT:    retl
+; CHECK-NEXT:    mov 1, %o0
+;
+; CHECK64-LABEL: test:
+; CHECK64:       ! %bb.0: ! %entry
+; CHECK64-NEXT:    andcc %o0, 1, %g0
+; CHECK64-NEXT:    bne %icc, .LBB0_2
+; CHECK64-NEXT:    nop
+; CHECK64-NEXT:  ! %bb.1: ! %if.end
+; CHECK64-NEXT:    retl
+; CHECK64-NEXT:    mov 2, %o0
+; CHECK64-NEXT:  .LBB0_2: ! %if.then
+; CHECK64-NEXT:    retl
+; CHECK64-NEXT:    mov 1, %o0
+entry:
+  %and = and i32 %a, 1
+  %tobool = icmp eq i32 %and, 0
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:
+  ret i32 1
+
+if.end:
+  ret i32 2
+}
+
+; Same as above, with select.
+define i32 @test_select(i32 %a) nounwind {
+; CHECK-LABEL: test_select:
+; CHECK:       ! %bb.0:
+; CHECK-NEXT:    andcc %o0, 1, %g0
+; CHECK-NEXT:    be .LBB1_2
+; CHECK-NEXT:    nop
+; CHECK-NEXT:  ! %bb.1:
+; CHECK-NEXT:    retl
+; CHECK-NEXT:    mov 2, %o0
+; CHECK-NEXT:  .LBB1_2:
+; CHECK-NEXT:    retl
+; CHECK-NEXT:    mov 1, %o0
+;
+; CHECK64-LABEL: test_select:
+; CHECK64:       ! %bb.0:
+; CHECK64-NEXT:    andcc %o0, 1, %g0
+; CHECK64-NEXT:    mov 2, %o0
+; CHECK64-NEXT:    retl
+; CHECK64-NEXT:    move %icc, 1, %o0
+  %and = and i32 %a, 1
+  %tobool = icmp eq i32 %and, 0
+  %ret = select i1 %tobool, i32 1, i32 2
+  ret i32 %ret
+}
+
+
+; No instruction can be changed to set ICC
+define i32 @no_candidate(i32 %a) nounwind {
+; CHECK-LABEL: no_candidate:
+; CHECK:       ! %bb.0: ! %entry
+; CHECK-NEXT:    cmp %o0, 0
+; CHECK-NEXT:    be .LBB2_2
+; CHECK-NEXT:    nop
+; CHECK-NEXT:  ! %bb.1: ! %if.then
+; CHECK-NEXT:    retl
+; CHECK-NEXT:    mov 1, %o0
+; CHECK-NEXT:  .LBB2_2: ! %if.end
+; CHECK-NEXT:    retl
+; CHECK-NEXT:    mov 2, %o0
+;
+; CHECK64-LABEL: no_candidate:
+; CHECK64:       ! %bb.0: ! %entry
+; CHECK64-NEXT:    cmp %o0, 0
+; CHECK64-NEXT:    be %icc, .LBB2_2
+; CHECK64-NEXT:    nop
+; CHECK64-NEXT:  ! %bb.1: ! %if.then
+; CHECK64-NEXT:    retl
+; CHECK64-NEXT:    mov 1, %o0
+; CHECK64-NEXT:  .LBB2_2: ! %if.end
+; CHECK64-NEXT:    retl
+; CHECK64-NEXT:    mov 2, %o0
+entry:
+  %tobool = icmp eq i32 %a, 0
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:
+  ret i32 1
+
+if.end:
+  ret i32 2
+}
+
+; Defining instruction and compare not in same block
+define i32 @not_same_block(i32 %a) nounwind {
+; CHECK-LABEL: not_same_block:
+; CHECK:       ! %bb.0: ! %entry
+; CHECK-NEXT:    and %o0, 1, %o0
+; CHECK-NEXT:  .LBB3_1: ! %if.then
+; CHECK-NEXT:    ! =>This Inner Loop Header: Depth=1
+; CHECK-NEXT:    cmp %o0, 0
+; CHECK-NEXT:    bne .LBB3_1
+; CHECK-NEXT:    nop
+; CHECK-NEXT:  ! %bb.2: ! %if.end
+; CHECK-NEXT:    retl
+; CHECK-NEXT:    mov 2, %o0
+;
+; CHECK64-LABEL: not_same_block:
+; CHECK64:       ! %bb.0: ! %entry
+; CHECK64-NEXT:    and %o0, 1, %o0
+; CHECK64-NEXT:  .LBB3_1: ! %if.then
+; CHECK64-NEXT:    ! =>This Inner Loop Header: Depth=1
+; CHECK64-NEXT:    cmp %o0, 0
+; CHECK64-NEXT:    bne %icc, .LBB3_1
+; CHECK64-NEXT:    nop
+; CHECK64-NEXT:  ! %bb.2: ! %if.end
+; CHECK64-NEXT:    retl
+; CHECK64-NEXT:    mov 2, %o0
+entry:
+  %and = and i32 %a, 1
+  br label %if.then
+
+if.then:
+  %tobool = icmp eq i32 %and, 0
+  br i1 %tobool, label %if.end, label %if.then
+  ret i32 1
+
+if.end:
+  ret i32 2
+}
+
+; Compare instruction is not checking equality
+define i32 @not_equality(i32 %a) nounwind {
+; CHECK-LABEL: not_equality:
+; CHECK:       ! %bb.0: ! %entry
+; CHECK-NEXT:    and %o0, 1, %o1
+; CHECK-NEXT:    cmp %o1, 0
+; CHECK-NEXT:    bl .LBB4_2
+; CHECK-NEXT:    nop
+; CHECK-NEXT:  ! %bb.1: ! %entry
+; CHECK-NEXT:    mov %o1, %o0
+; CHECK-NEXT:  .LBB4_2: ! %entry
+; CHECK-NEXT:    retl
+; CHECK-NEXT:    nop
+;
+; CHECK64-LABEL: not_equality:
+; CHECK64:       ! %bb.0: ! %entry
+; CHECK64-NEXT:    and %o0, 1, %o1
+; CHECK64-NEXT:    cmp %o1, 0
+; CHECK64-NEXT:    movl %icc, %o0, %o1
+; CHECK64-NEXT:    retl
+; CHECK64-NEXT:    mov %o1, %o0
+entry:
+  %and = and i32 %a, 1
+  %cmp = icmp slt i32 %and, 0
----------------
s-barannikov wrote:

This is always false

https://github.com/llvm/llvm-project/pull/167140