[llvm] [CGP] Despeculate ctlz/cttz with "illegal" integer types (PR #137197)

[Luke Lau via llvm-commits]

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@@ -441,33 +444,35 @@ define i64 @test_cttz_i64(i64 %a) nounwind {
 ;
 ; RV32M-LABEL: test_cttz_i64:
 ; RV32M:       # %bb.0:
+; RV32M-NEXT:    or a2, a0, a1
+; RV32M-NEXT:    beqz a2, .LBB3_3
+; RV32M-NEXT:  # %bb.1: # %cond.false
 ; RV32M-NEXT:    lui a2, 30667
 ; RV32M-NEXT:    addi a3, a2, 1329
 ; RV32M-NEXT:    lui a2, %hi(.LCPI3_0)
 ; RV32M-NEXT:    addi a2, a2, %lo(.LCPI3_0)
-; RV32M-NEXT:    bnez a1, .LBB3_3
-; RV32M-NEXT:  # %bb.1:
-; RV32M-NEXT:    li a1, 32
-; RV32M-NEXT:    beqz a0, .LBB3_4
-; RV32M-NEXT:  .LBB3_2:
-; RV32M-NEXT:    neg a1, a0
-; RV32M-NEXT:    and a0, a0, a1
+; RV32M-NEXT:    bnez a0, .LBB3_4
+; RV32M-NEXT:  # %bb.2: # %cond.false
+; RV32M-NEXT:    neg a0, a1
+; RV32M-NEXT:    and a0, a1, a0
 ; RV32M-NEXT:    mul a0, a0, a3
 ; RV32M-NEXT:    srli a0, a0, 27
 ; RV32M-NEXT:    add a0, a2, a0
 ; RV32M-NEXT:    lbu a0, 0(a0)
+; RV32M-NEXT:    addi a0, a0, 32
 ; RV32M-NEXT:    li a1, 0
 ; RV32M-NEXT:    ret
 ; RV32M-NEXT:  .LBB3_3:
-; RV32M-NEXT:    neg a4, a1
-; RV32M-NEXT:    and a1, a1, a4
-; RV32M-NEXT:    mul a1, a1, a3
-; RV32M-NEXT:    srli a1, a1, 27
-; RV32M-NEXT:    add a1, a2, a1
-; RV32M-NEXT:    lbu a1, 0(a1)
-; RV32M-NEXT:    bnez a0, .LBB3_2
+; RV32M-NEXT:    li a1, 0
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lukel97 wrote:

Not related to this patch, but a1 needs to be zero to get here, can we remove this li?

https://github.com/llvm/llvm-project/pull/137197