[CodeGen] Pre-commit test case related to ComputeNumSignBits for SHL (#97695)

Adding test cases aiming at showing possibility to look through
ZERO_EXTEND/ANY_EXTEND when computing number of sign bits for an
SHL node. If all extended bits are shifted out we can analyze the
operand that is extended.

Author: bjope

llvm/test/CodeGen/X86/computenumsignbits-shl.ll

@@ -0,0 +1,191 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=x86_64-linux | FileCheck %s --check-prefix=X64
+
+; Verify that we can look through a ZERO_EXTEND/ANY_EXTEND when doing
+; ComputeNumSignBits for SHL.
+; We use the (sshlsat x, c) -> (shl x, c) fold as verification.
+; That fold should happen if c is less than the number of sign bits in x
+
+define void @computeNumSignBits_shl_zext_1(i8 %x, ptr %p) nounwind {
+; X64-LABEL: computeNumSignBits_shl_zext_1:
+; X64:       # %bb.0:
+; X64-NEXT:    sarb $5, %dil
+; X64-NEXT:    movzbl %dil, %eax
+; X64-NEXT:    movl %eax, %ecx
+; X64-NEXT:    shll $10, %ecx
+; X64-NEXT:    xorl %edx, %edx
+; X64-NEXT:    testw %cx, %cx
+; X64-NEXT:    sets %dl
+; X64-NEXT:    addl $32767, %edx # imm = 0x7FFF
+; X64-NEXT:    movl %eax, %edi
+; X64-NEXT:    shll $11, %edi
+; X64-NEXT:    movswl %di, %r8d
+; X64-NEXT:    shrl %r8d
+; X64-NEXT:    cmpw %r8w, %cx
+; X64-NEXT:    cmovnel %edx, %edi
+; X64-NEXT:    movw %di, (%rsi)
+; X64-NEXT:    movl %eax, %edi
+; X64-NEXT:    shll $12, %edi
+; X64-NEXT:    movswl %di, %r8d
+; X64-NEXT:    shrl $2, %r8d
+; X64-NEXT:    cmpw %r8w, %cx
+; X64-NEXT:    cmovnel %edx, %edi
+; X64-NEXT:    movw %di, (%rsi)
+; X64-NEXT:    shll $13, %eax
+; X64-NEXT:    movswl %ax, %edi
+; X64-NEXT:    shrl $3, %edi
+; X64-NEXT:    cmpw %di, %cx
+; X64-NEXT:    cmovnel %edx, %eax
+; X64-NEXT:    movw %ax, (%rsi)
+; X64-NEXT:    retq
+  %ashr = ashr i8 %x, 5
+  %zext = zext i8 %ashr to i16
+  %nsb4 = shl i16 %zext, 10
+  ; Expecting (sshlsat x, c) -> (shl x, c) fold.
+  %tmp1 = call i16 @llvm.sshl.sat.i16(i16 %nsb4, i16 1)
+  store volatile i16 %tmp1, ptr %p
+  ; Expecting (sshlsat x, c) -> (shl x, c) fold.
+  %tmp2 = call i16 @llvm.sshl.sat.i16(i16 %nsb4, i16 2)
+  store volatile i16 %tmp2, ptr %p
+  ; Expecting (sshlsat x, c) -> (shl x, c) fold.
+  %tmp3 = call i16 @llvm.sshl.sat.i16(i16 %nsb4, i16 3)
+  store volatile i16 %tmp3, ptr %p
+  ret void
+}
+
+define void @computeNumSignBits_shl_zext_2(i8 %x, ptr %p) nounwind {
+; X64-LABEL: computeNumSignBits_shl_zext_2:
+; X64:       # %bb.0:
+; X64-NEXT:    sarb $5, %dil
+; X64-NEXT:    movzbl %dil, %eax
+; X64-NEXT:    movl %eax, %ecx
+; X64-NEXT:    shll $10, %ecx
+; X64-NEXT:    xorl %edx, %edx
+; X64-NEXT:    testw %cx, %cx
+; X64-NEXT:    sets %dl
+; X64-NEXT:    addl $32767, %edx # imm = 0x7FFF
+; X64-NEXT:    shll $14, %eax
+; X64-NEXT:    movswl %ax, %edi
+; X64-NEXT:    shrl $4, %edi
+; X64-NEXT:    cmpw %di, %cx
+; X64-NEXT:    cmovnel %edx, %eax
+; X64-NEXT:    movw %ax, (%rsi)
+; X64-NEXT:    retq
+  %ashr = ashr i8 %x, 5
+  %zext = zext i8 %ashr to i16
+  %nsb4 = shl i16 %zext, 10
+  ; 4 sign bits. Not expecting (sshlsat x, c) -> (shl x, c) fold.
+  %tmp4 = call i16 @llvm.sshl.sat.i16(i16 %nsb4, i16 4)
+  store volatile i16 %tmp4, ptr %p
+  ret void
+}
+
+define void @computeNumSignBits_shl_zext_vec_1(<2 x i8> %x, ptr %p) nounwind {
+; X64-LABEL: computeNumSignBits_shl_zext_vec_1:
+; X64:       # %bb.0:
+; X64-NEXT:    psrlw $5, %xmm0
+; X64-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
+; X64-NEXT:    movdqa {{.*#+}} xmm1 = [4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4]
+; X64-NEXT:    pxor %xmm1, %xmm0
+; X64-NEXT:    psubb %xmm1, %xmm0
+; X64-NEXT:    pxor %xmm1, %xmm1
+; X64-NEXT:    punpcklbw {{.*#+}} xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1],xmm0[2],xmm1[2],xmm0[3],xmm1[3],xmm0[4],xmm1[4],xmm0[5],xmm1[5],xmm0[6],xmm1[6],xmm0[7],xmm1[7]
+; X64-NEXT:    pmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0 # [1024,4096,u,u,u,u,u,u]
+; X64-NEXT:    movdqa {{.*#+}} xmm2 = [32768,32768,32768,32768,32768,32768,32768,32768]
+; X64-NEXT:    pand %xmm0, %xmm2
+; X64-NEXT:    pcmpgtw %xmm0, %xmm1
+; X64-NEXT:    pandn {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1
+; X64-NEXT:    por %xmm2, %xmm1
+; X64-NEXT:    movdqa %xmm0, %xmm2
+; X64-NEXT:    paddw %xmm0, %xmm2
+; X64-NEXT:    movdqa %xmm2, %xmm3
+; X64-NEXT:    psraw $1, %xmm3
+; X64-NEXT:    pcmpeqw %xmm0, %xmm3
+; X64-NEXT:    movdqa %xmm3, %xmm0
+; X64-NEXT:    pandn %xmm1, %xmm0
+; X64-NEXT:    pand %xmm2, %xmm3
+; X64-NEXT:    por %xmm0, %xmm3
+; X64-NEXT:    movd %xmm3, (%rdi)
+; X64-NEXT:    retq
+  %ashr = ashr <2 x i8> %x, <i8 5, i8 5>
+  %zext = zext <2 x i8> %ashr to <2 x i16>
+  %nsb4_2 = shl <2 x i16> %zext, <i16 10, i16 12>
+  ; Expecting (sshlsat x, c) -> (shl x, c) fold.
+  %tmp1 = call <2 x i16> @llvm.sshl.sat.v2i16(<2 x i16> %nsb4_2, <2 x i16> <i16 1, i16 1>)
+  store volatile <2 x i16> %tmp1, ptr %p
+  ret void
+}
+
+define void @computeNumSignBits_shl_zext_vec_2(<2 x i8> %x, ptr %p) nounwind {
+; X64-LABEL: computeNumSignBits_shl_zext_vec_2:
+; X64:       # %bb.0:
+; X64-NEXT:    psrlw $5, %xmm0
+; X64-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
+; X64-NEXT:    movdqa {{.*#+}} xmm1 = [4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4]
+; X64-NEXT:    pxor %xmm1, %xmm0
+; X64-NEXT:    psubb %xmm1, %xmm0
+; X64-NEXT:    pxor %xmm1, %xmm1
+; X64-NEXT:    punpcklbw {{.*#+}} xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1],xmm0[2],xmm1[2],xmm0[3],xmm1[3],xmm0[4],xmm1[4],xmm0[5],xmm1[5],xmm0[6],xmm1[6],xmm0[7],xmm1[7]
+; X64-NEXT:    pmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0 # [1024,4096,u,u,u,u,u,u]
+; X64-NEXT:    movdqa {{.*#+}} xmm2 = [32768,32768,32768,32768,32768,32768,32768,32768]
+; X64-NEXT:    pand %xmm0, %xmm2
+; X64-NEXT:    pcmpgtw %xmm0, %xmm1
+; X64-NEXT:    pandn {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1
+; X64-NEXT:    por %xmm2, %xmm1
+; X64-NEXT:    movdqa %xmm0, %xmm2
+; X64-NEXT:    psllw $2, %xmm2
+; X64-NEXT:    movdqa %xmm2, %xmm3
+; X64-NEXT:    psraw $2, %xmm3
+; X64-NEXT:    pcmpeqw %xmm0, %xmm3
+; X64-NEXT:    movdqa %xmm3, %xmm0
+; X64-NEXT:    pandn %xmm1, %xmm0
+; X64-NEXT:    pand %xmm2, %xmm3
+; X64-NEXT:    por %xmm0, %xmm3
+; X64-NEXT:    movd %xmm3, (%rdi)
+; X64-NEXT:    retq
+  %ashr = ashr <2 x i8> %x, <i8 5, i8 5>
+  %zext = zext <2 x i8> %ashr to <2 x i16>
+  %nsb4_2 = shl <2 x i16> %zext, <i16 10, i16 12>
+  ; Not expecting (sshlsat x, c) -> (shl x, c) fold.
+  ; Because only 2 sign bits in element 1.
+  %tmp1 = call <2 x i16> @llvm.sshl.sat.v2i16(<2 x i16> %nsb4_2, <2 x i16> <i16 2, i16 2>)
+  store volatile <2 x i16> %tmp1, ptr %p
+  ret void
+}
+
+define void @computeNumSignBits_shl_zext_vec_3(<2 x i8> %x, ptr %p) nounwind {
+; X64-LABEL: computeNumSignBits_shl_zext_vec_3:
+; X64:       # %bb.0:
+; X64-NEXT:    psrlw $5, %xmm0
+; X64-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
+; X64-NEXT:    movdqa {{.*#+}} xmm1 = [4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4]
+; X64-NEXT:    pxor %xmm1, %xmm0
+; X64-NEXT:    psubb %xmm1, %xmm0
+; X64-NEXT:    pxor %xmm1, %xmm1
+; X64-NEXT:    punpcklbw {{.*#+}} xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1],xmm0[2],xmm1[2],xmm0[3],xmm1[3],xmm0[4],xmm1[4],xmm0[5],xmm1[5],xmm0[6],xmm1[6],xmm0[7],xmm1[7]
+; X64-NEXT:    pmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0 # [16384,4096,u,u,u,u,u,u]
+; X64-NEXT:    movdqa {{.*#+}} xmm2 = [32768,32768,32768,32768,32768,32768,32768,32768]
+; X64-NEXT:    pand %xmm0, %xmm2
+; X64-NEXT:    pcmpgtw %xmm0, %xmm1
+; X64-NEXT:    pandn {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1
+; X64-NEXT:    por %xmm2, %xmm1
+; X64-NEXT:    movdqa %xmm0, %xmm2
+; X64-NEXT:    paddw %xmm0, %xmm2
+; X64-NEXT:    movdqa %xmm2, %xmm3
+; X64-NEXT:    psraw $1, %xmm3
+; X64-NEXT:    pcmpeqw %xmm0, %xmm3
+; X64-NEXT:    movdqa %xmm3, %xmm0
+; X64-NEXT:    pandn %xmm1, %xmm0
+; X64-NEXT:    pand %xmm2, %xmm3
+; X64-NEXT:    por %xmm0, %xmm3
+; X64-NEXT:    movd %xmm3, (%rdi)
+; X64-NEXT:    retq
+  %ashr = ashr <2 x i8> %x, <i8 5, i8 5>
+  %zext = zext <2 x i8> %ashr to <2 x i16>
+  %nsb1_2 = shl <2 x i16> %zext, <i16 14, i16 12>
+  ; Not expecting (sshlsat x, c) -> (shl x, c) fold.
+  ; Because all sign bits shifted out for element 0
+  %tmp1 = call <2 x i16> @llvm.sshl.sat.v2i16(<2 x i16> %nsb1_2, <2 x i16> <i16 1, i16 1>)
+  store volatile <2 x i16> %tmp1, ptr %p
+  ret void
+}