[llvm-bugs] [Bug 39665] New: [X86][SSE] Masked memory op expansion could use MOVMSK to simplify mask handling

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=39665

            Bug ID: 39665
           Summary: [X86][SSE] Masked memory op expansion could use MOVMSK
                    to simplify mask handling
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: llvm-dev at redking.me.uk
                CC: craig.topper at gmail.com, llvm-bugs at lists.llvm.org,
                    llvm-dev at redking.me.uk, spatel+llvm at rotateright.com

define <2 x double> @load_v2f64_v2i64(<2 x i64> %trigger, <2 x double>* %addr,
<2 x double> %dst) {
; SSE42-LABEL: load_v2f64_v2i64:
; SSE42:       ## %bb.0:
; SSE42-NEXT:    pxor %xmm2, %xmm2
; SSE42-NEXT:    pcmpeqq %xmm0, %xmm2
; SSE42-NEXT:    pextrb $0, %xmm2, %eax
; SSE42-NEXT:    testb $1, %al
; SSE42-NEXT:    je LBB1_2
; SSE42-NEXT:  ## %bb.1: ## %cond.load
; SSE42-NEXT:    movlpd {{.*#+}} xmm1 = mem[0],xmm1[1]
; SSE42-NEXT:  LBB1_2: ## %else
; SSE42-NEXT:    pextrb $8, %xmm2, %eax
; SSE42-NEXT:    testb $1, %al
; SSE42-NEXT:    je LBB1_4
; SSE42-NEXT:  ## %bb.3: ## %cond.load1
; SSE42-NEXT:    movhpd {{.*#+}} xmm1 = xmm1[0],mem[0]
; SSE42-NEXT:  LBB1_4: ## %else2
; SSE42-NEXT:    movapd %xmm1, %xmm0
; SSE42-NEXT:    retq
  %mask = icmp eq <2 x i64> %trigger, zeroinitializer
  %res = call <2 x double> @llvm.masked.load.v2f64.p0v2f64(<2 x double>* %addr,
i32 4, <2 x i1>%mask, <2 x double>%dst)
  ret <2 x double> %res
}
declare <2 x double> @llvm.masked.load.v2f64.p0v2f64(<2 x double>*, i32, <2 x
i1>, <2 x double>)

This can replace all the pextrb with a single movmsk to something like:

  pxor %xmm2, %xmm2
  pcmpeqq %xmm0, %xmm2
  movmskpd %xmm2, %eax
  testb $1, %al
  jne LBB1_2
## %bb.1: ## %cond.load
  movlpd {{.*#+}} xmm1 = mem[0],xmm1[1]
LBB1_2: ## %else
  testb $2, %al
  jne LBB1_4
## %bb.3: ## %cond.load1
  movhpd {{.*#+}} xmm1 = xmm1[0],mem[0]
LBB1_4: ## %else2
  movapd %xmm1, %xmm0
  retq

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