[X86] Added BitScanForward/BitScanReverse memory folding + tests

llvm-svn: 239257

2 files changed, 57 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 43decf7cdda..44068f9190b 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -433,6 +433,12 @@ X86InstrInfo::X86InstrInfo(X86Subtarget &STI)
   }
 
   static const X86MemoryFoldTableEntry MemoryFoldTable1[] = {
+    { X86::BSF16rr,         X86::BSF16rm,             0 },
+    { X86::BSF32rr,         X86::BSF32rm,             0 },
+    { X86::BSF64rr,         X86::BSF64rm,             0 },
+    { X86::BSR16rr,         X86::BSR16rm,             0 },
+    { X86::BSR32rr,         X86::BSR32rm,             0 },
+    { X86::BSR64rr,         X86::BSR64rm,             0 },
     { X86::CMP16rr,         X86::CMP16rm,             0 },
     { X86::CMP32rr,         X86::CMP32rm,             0 },
     { X86::CMP64rr,         X86::CMP64rm,             0 },
diff --git a/llvm/test/CodeGen/X86/stack-folding-x86_64.ll b/llvm/test/CodeGen/X86/stack-folding-x86_64.ll
new file mode 100644
index 00000000000..211227916a0
--- /dev/null
+++ b/llvm/test/CodeGen/X86/stack-folding-x86_64.ll
@@ -0,0 +1,51 @@
+; RUN: llc -O3 -disable-peephole -mtriple=x86_64-unknown-unknown -mcpu=x86-64 < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-unknown"
+
+; Stack reload folding tests.
+;
+; By including a nop call with sideeffects we can force a partial register spill of the
+; relevant registers and check that the reload is correctly folded into the instruction.
+
+;TODO stack_fold_bsf_i16
+declare i16 @llvm.cttz.i16(i16, i1)
+
+define i32 @stack_fold_bsf_i32(i32 %a0) {
+  ;CHECK-LABEL: stack_fold_bsf_i32
+  ;CHECK:       bsfl {{-?[0-9]*}}(%rsp), %eax {{.*#+}} 4-byte Folded Reload
+  %1 = tail call i64 asm sideeffect "nop", "=x,~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15}"()
+  %2 = call i32 @llvm.cttz.i32(i32 %a0, i1 -1)
+  ret i32 %2
+}
+declare i32 @llvm.cttz.i32(i32, i1)
+
+define i64 @stack_fold_bsf_i64(i64 %a0) {
+  ;CHECK-LABEL: stack_fold_bsf_i64
+  ;CHECK:       bsfq {{-?[0-9]*}}(%rsp), %rax {{.*#+}} 8-byte Folded Reload
+  %1 = tail call i64 asm sideeffect "nop", "=x,~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15}"()
+  %2 = call i64 @llvm.cttz.i64(i64 %a0, i1 -1)
+  ret i64 %2
+}
+declare i64 @llvm.cttz.i64(i64, i1)
+
+;TODO stack_fold_bsr_i16
+declare i16 @llvm.ctlz.i16(i16, i1)
+
+define i32 @stack_fold_bsr_i32(i32 %a0) {
+  ;CHECK-LABEL: stack_fold_bsr_i32
+  ;CHECK:       bsrl {{-?[0-9]*}}(%rsp), %eax {{.*#+}} 4-byte Folded Reload
+  %1 = tail call i64 asm sideeffect "nop", "=x,~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15}"()
+  %2 = call i32 @llvm.ctlz.i32(i32 %a0, i1 -1)
+  ret i32 %2
+}
+declare i32 @llvm.ctlz.i32(i32, i1)
+
+define i64 @stack_fold_bsr_i64(i64 %a0) {
+  ;CHECK-LABEL: stack_fold_bsr_i64
+  ;CHECK:       bsrq {{-?[0-9]*}}(%rsp), %rax {{.*#+}} 8-byte Folded Reload
+  %1 = tail call i64 asm sideeffect "nop", "=x,~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15}"()
+  %2 = call i64 @llvm.ctlz.i64(i64 %a0, i1 -1)
+  ret i64 %2
+}
+declare i64 @llvm.ctlz.i64(i64, i1)