[ARM] Merging 64-bit divmod lib calls into one

When div+rem calls on the same arguments are found, the ARM back-end merges the
two calls into one __aeabi_divmod call for up to 32-bits values. However,
for 64-bit values, which also have a lib call (__aeabi_ldivmod), it wasn't
merging the calls, and thus calling ldivmod twice and spilling the temporary
results, which generated pretty bad code.

This patch legalises 64-bit lib calls for divmod, so that now all the spilling
and the second call are gone. It also relaxes the DivRem combiner a bit on the
legal type check, since it was already checking for isLegalOrCustom on every
value, so the extra check for isTypeLegal was redundant.

This patch fixes PR17193 (and a long time FIXME in the tests).

llvm-svn: 262507

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/test/CodeGen/ARM/divmod-eabi.ll b/llvm/test/CodeGen/ARM/divmod-eabi.ll
index 35f2014317b..29c7fe0ff86 100644
--- a/llvm/test/CodeGen/ARM/divmod-eabi.ll
+++ b/llvm/test/CodeGen/ARM/divmod-eabi.ll
@@ -79,7 +79,6 @@ entry:
   ret i32 %add2
 }
 
-; FIXME: AEABI is not lowering long u/srem into u/ldivmod
 define i64 @longf(i64 %a, i64 %b) {
 ; EABI-LABEL: longf:
 ; DARWIN-LABEL: longf:
@@ -87,6 +86,9 @@ entry:
   %div = sdiv i64 %a, %b
   %rem = srem i64 %a, %b
 ; EABI: __aeabi_ldivmod
+; EABI-NEXT: adds r0
+; EABI-NEXT: adc r1
+; EABI-NOT: __aeabi_ldivmod
 ; DARWIN: ___divdi3
 ; DARWIN: mov [[div1:r[0-9]+]], r0
 ; DARWIN: mov [[div2:r[0-9]+]], r1