[llvm] [DAG] Fold logic of zero-checks to multiplication for MinSize (PR #171805)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,131 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv64 -mattr=+m -enable-machine-outliner=never < %s | FileCheck %s
+
+define i1 @foldLogicSetCCToMul0(i16 zeroext %a, i16 zeroext %b) minsize {
+; CHECK-LABEL: foldLogicSetCCToMul0:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    mul a0, a0, a1
+; CHECK-NEXT:    seqz a0, a0
+; CHECK-NEXT:    ret
+entry:
+  %cmp1 = icmp eq i16 %a, 0
+  %cmp2 = icmp eq i16 %b, 0
+  %or = or i1 %cmp1, %cmp2
+  ret i1 %or
+}
+
+define i1 @foldLogicSetCCToMul1(i16 zeroext %a, i16 zeroext %b) minsize {
+; CHECK-LABEL: foldLogicSetCCToMul1:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    mul a0, a0, a1
+; CHECK-NEXT:    snez a0, a0
+; CHECK-NEXT:    ret
+entry:
+  %cmp1 = icmp ne i16 %a, 0
+  %cmp2 = icmp ne i16 %b, 0
+  %and = and i1 %cmp1, %cmp2
+  ret i1 %and
+}
+
+define i1 @foldLogicSetCCToMul2(i64 %a, i64 %b) minsize {
+; CHECK-LABEL: foldLogicSetCCToMul2:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    seqz a0, a0
+; CHECK-NEXT:    seqz a1, a1
+; CHECK-NEXT:    or a0, a0, a1
+; CHECK-NEXT:    ret
+entry:
+  %cmp1 = icmp eq i64 %a, 0
+  %cmp2 = icmp eq i64 %b, 0
+  %or = or i1 %cmp1, %cmp2
+  ret i1 %or
+}
+
+define i1 @foldLogicSetCCToMul3(i16 zeroext %a, i16 zeroext %b) {
+; CHECK-LABEL: foldLogicSetCCToMul3:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    seqz a0, a0
+; CHECK-NEXT:    seqz a1, a1
+; CHECK-NEXT:    or a0, a0, a1
+; CHECK-NEXT:    ret
+entry:
+  %cmp1 = icmp eq i16 %a, 0
+  %cmp2 = icmp eq i16 %b, 0
+  %or = or i1 %cmp1, %cmp2
+  ret i1 %or
+}
+
+define i1 @foldLogicSetCCToMul4(i16 zeroext %a, i16 zeroext %b) minsize {
+; CHECK-LABEL: foldLogicSetCCToMul4:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    seqz a0, a0
+; CHECK-NEXT:    snez a1, a1
+; CHECK-NEXT:    or a0, a0, a1
+; CHECK-NEXT:    ret
+entry:
+  %cmp1 = icmp eq i16 %a, 0
+  %cmp2 = icmp ne i16 %b, 0
+  %or = or i1 %cmp1, %cmp2
+  ret i1 %or
+}
+
+define i1 @foldLogicSetCCToMul5(i16 zeroext %a, i16 zeroext %b) minsize {
+; CHECK-LABEL: foldLogicSetCCToMul5:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addi a0, a0, -1
+; CHECK-NEXT:    seqz a0, a0
+; CHECK-NEXT:    seqz a1, a1
+; CHECK-NEXT:    or a0, a0, a1
+; CHECK-NEXT:    ret
+entry:
+  %cmp1 = icmp eq i16 %a, 1;
+  %cmp2 = icmp eq i16 %b, 0
+  %or = or i1 %cmp1, %cmp2
+  ret i1 %or
+}
+
+define i1 @foldLogicSetCCToMul6(i16 zeroext %a, i16 zeroext %b) minsize {
+; CHECK-LABEL: foldLogicSetCCToMul6:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    seqz a0, a0
+; CHECK-NEXT:    addi a1, a1, -1
+; CHECK-NEXT:    seqz a1, a1
+; CHECK-NEXT:    or a0, a0, a1
+; CHECK-NEXT:    ret
+entry:
+  %cmp1 = icmp eq i16 %a, 0;
+  %cmp2 = icmp eq i16 %b, 1
+  %or = or i1 %cmp1, %cmp2
+  ret i1 %or
+}
+
+define i1 @foldLogicSetCCToMul7(i16 zeroext %a, i32 signext %b) minsize {
----------------
arsenm wrote:

These test function names could all be better. In particular the negative tests all are "fold". It's generally easier to understand the tests if they spell out which combination they are stressing than the same function with a number suffix 

https://github.com/llvm/llvm-project/pull/171805