[llvm] [X86][APX] Optimize usub.sat(X, 1) to cmp+adc with NDD (PR #208475)

[via llvm-commits]

================
@@ -1238,3 +1238,128 @@ bb2:                                              ; preds = %bb2, %bb1
   store ptr null, ptr %arg2, align 8
   br i1 %arg3, label %bb1, label %bb2
 }
+;
+define i8 @usubsat8_const1(i8 noundef %a) {
+; CHECK-LABEL: usubsat8_const1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    cmpb $1, %dil # encoding: [0x40,0x80,0xff,0x01]
+; CHECK-NEXT:    adcb $-1, %dil, %al # encoding: [0x62,0xf4,0x7c,0x18,0x80,0xd7,0xff]
+; CHECK-NEXT:    retq # encoding: [0xc3]
+;
+; NF-LABEL: usubsat8_const1:
+; NF:       # %bb.0: # %entry
+; NF-NEXT:    cmpb $1, %dil # encoding: [0x40,0x80,0xff,0x01]
+; NF-NEXT:    adcb $-1, %dil, %al # encoding: [0x62,0xf4,0x7c,0x18,0x80,0xd7,0xff]
+; NF-NEXT:    retq # encoding: [0xc3]
+entry:
+    %sub = call i8 @llvm.usub.sat.i8(i8 %a, i8 1)
+    ret i8 %sub
+}
+
+define i16 @usubsat16_const1(i16 noundef %a) {
+; CHECK-LABEL: usubsat16_const1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    cmpw $1, %di # encoding: [0x66,0x83,0xff,0x01]
+; CHECK-NEXT:    adcw $-1, %di, %ax # encoding: [0x62,0xf4,0x7d,0x18,0x83,0xd7,0xff]
+; CHECK-NEXT:    retq # encoding: [0xc3]
+;
+; NF-LABEL: usubsat16_const1:
+; NF:       # %bb.0: # %entry
+; NF-NEXT:    cmpw $1, %di # encoding: [0x66,0x83,0xff,0x01]
+; NF-NEXT:    adcw $-1, %di, %ax # encoding: [0x62,0xf4,0x7d,0x18,0x83,0xd7,0xff]
+; NF-NEXT:    retq # encoding: [0xc3]
+entry:
+    %sub = call i16 @llvm.usub.sat.i16(i16 %a, i16 1)
+    ret i16 %sub
+}
+
+define i32 @usubsat32_const1(i32 noundef %a) {
+; CHECK-LABEL: usubsat32_const1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    cmpl $1, %edi # encoding: [0x83,0xff,0x01]
+; CHECK-NEXT:    adcl $-1, %edi, %eax # encoding: [0x62,0xf4,0x7c,0x18,0x83,0xd7,0xff]
+; CHECK-NEXT:    retq # encoding: [0xc3]
+;
+; NF-LABEL: usubsat32_const1:
+; NF:       # %bb.0: # %entry
+; NF-NEXT:    cmpl $1, %edi # encoding: [0x83,0xff,0x01]
+; NF-NEXT:    adcl $-1, %edi, %eax # encoding: [0x62,0xf4,0x7c,0x18,0x83,0xd7,0xff]
+; NF-NEXT:    retq # encoding: [0xc3]
+entry:
+    %sub = call i32 @llvm.usub.sat.i32(i32 %a, i32 1)
+    ret i32 %sub
+}
+
+define i64 @usubsat64_const1(i64 noundef %a) {
+; CHECK-LABEL: usubsat64_const1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    cmpq $1, %rdi # encoding: [0x48,0x83,0xff,0x01]
+; CHECK-NEXT:    adcq $-1, %rdi, %rax # encoding: [0x62,0xf4,0xfc,0x18,0x83,0xd7,0xff]
+; CHECK-NEXT:    retq # encoding: [0xc3]
+;
+; NF-LABEL: usubsat64_const1:
+; NF:       # %bb.0: # %entry
+; NF-NEXT:    cmpq $1, %rdi # encoding: [0x48,0x83,0xff,0x01]
+; NF-NEXT:    adcq $-1, %rdi, %rax # encoding: [0x62,0xf4,0xfc,0x18,0x83,0xd7,0xff]
+; NF-NEXT:    retq # encoding: [0xc3]
+entry:
+    %sub = call i64 @llvm.usub.sat.i64(i64 %a, i64 1)
+    ret i64 %sub
+}
+
+define i32 @usubsat32_var(i32 noundef %a, i32 noundef %b) {
+; CHECK-LABEL: usubsat32_var:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    xorl %eax, %eax # encoding: [0x31,0xc0]
+; CHECK-NEXT:    subl %esi, %edi # EVEX TO LEGACY Compression encoding: [0x29,0xf7]
+; CHECK-NEXT:    cmovael %edi, %eax # EVEX TO LEGACY Compression encoding: [0x0f,0x43,0xc7]
+; CHECK-NEXT:    retq # encoding: [0xc3]
+;
+; NF-LABEL: usubsat32_var:
+; NF:       # %bb.0: # %entry
+; NF-NEXT:    xorl %eax, %eax # encoding: [0x31,0xc0]
+; NF-NEXT:    subl %esi, %edi # EVEX TO LEGACY Compression encoding: [0x29,0xf7]
+; NF-NEXT:    cmovael %edi, %eax # EVEX TO LEGACY Compression encoding: [0x0f,0x43,0xc7]
+; NF-NEXT:    retq # encoding: [0xc3]
+entry:
+    %sub = call i32 @llvm.usub.sat.i32(i32 %a, i32 %b)
+    ret i32 %sub
+}
+
+define i32 @usubsat32_const123(i32 noundef %a) {
+; CHECK-LABEL: usubsat32_const123:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    xorl %eax, %eax # encoding: [0x31,0xc0]
+; CHECK-NEXT:    subl $123, %edi # EVEX TO LEGACY Compression encoding: [0x83,0xef,0x7b]
+; CHECK-NEXT:    cmovael %edi, %eax # EVEX TO LEGACY Compression encoding: [0x0f,0x43,0xc7]
+; CHECK-NEXT:    retq # encoding: [0xc3]
+;
+; NF-LABEL: usubsat32_const123:
+; NF:       # %bb.0: # %entry
+; NF-NEXT:    xorl %eax, %eax # encoding: [0x31,0xc0]
+; NF-NEXT:    subl $123, %edi # EVEX TO LEGACY Compression encoding: [0x83,0xef,0x7b]
+; NF-NEXT:    cmovael %edi, %eax # EVEX TO LEGACY Compression encoding: [0x0f,0x43,0xc7]
+; NF-NEXT:    retq # encoding: [0xc3]
+entry:
+    %sub = call i32 @llvm.usub.sat.i32(i32 %a, i32 123)
+    ret i32 %sub
+}
+
+define i32 @uaddsat32_const1(i32 noundef %a) {
+; CHECK-LABEL: uaddsat32_const1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    incl %edi, %eax # encoding: [0x62,0xf4,0x7c,0x18,0xff,0xc7]
+; CHECK-NEXT:    movl $-1, %ecx # encoding: [0xb9,0xff,0xff,0xff,0xff]
+; CHECK-NEXT:    cmovel %ecx, %eax # EVEX TO LEGACY Compression encoding: [0x0f,0x44,0xc1]
+; CHECK-NEXT:    retq # encoding: [0xc3]
+;
+; NF-LABEL: uaddsat32_const1:
+; NF:       # %bb.0: # %entry
+; NF-NEXT:    incl %edi, %eax # encoding: [0x62,0xf4,0x7c,0x18,0xff,0xc7]
+; NF-NEXT:    movl $-1, %ecx # encoding: [0xb9,0xff,0xff,0xff,0xff]
+; NF-NEXT:    cmovel %ecx, %eax # EVEX TO LEGACY Compression encoding: [0x0f,0x44,0xc1]
+; NF-NEXT:    retq # encoding: [0xc3]
+entry:
+    %add = call i32 @llvm.uadd.sat.i32(i32 %a, i32 1)
----------------
AntonyCJ30 wrote:

Added uaddsat32_const_neg1 test case. PTAL.

https://github.com/llvm/llvm-project/pull/208475