Use doxygen comment syntax.

[oota-llvm.git] / lib / Target / ARM / README.txt

diff --git a/lib/Target/ARM/README.txt b/lib/Target/ARM/README.txt
index 3db8f54f50ca1319e37e18beca1d7fac5829d180..068c441ed737626486e58d3d0f8f8a98cbb7b240 100644 (file)
--- a/lib/Target/ARM/README.txt
+++ b/lib/Target/ARM/README.txt
@@ -186,24 +186,19 @@ double bar(double x) {
 }
 
 _bar:
-       sub sp, sp, #16
-       str r4, [sp, #+12]
-       str r5, [sp, #+8]
-       str lr, [sp, #+4]
-       mov r4, r0
-       mov r5, r1
-       ldr r0, LCPI2_0
-       bl _foo
-       fmsr f0, r0
-       fcvtsd d0, f0
-       fmdrr d1, r4, r5
-       faddd d0, d0, d1
-       fmrrd r0, r1, d0
-       ldr lr, [sp, #+4]
-       ldr r5, [sp, #+8]
-       ldr r4, [sp, #+12]
-       add sp, sp, #16
-       bx lr
+        stmfd sp!, {r4, r5, r7, lr}
+        add r7, sp, #8
+        mov r4, r0
+        mov r5, r1
+        fldd d0, LCPI1_0
+        fmrrd r0, r1, d0
+        bl _foo
+        fmdrr d0, r4, r5
+        fmsr s2, r0
+        fsitod d1, s2
+        faddd d0, d1, d0
+        fmrrd r0, r1, d0
+        ldmfd sp!, {r4, r5, r7, pc}
 
 Ignore the prologue and epilogue stuff for a second. Note 
        mov r4, r0
@@ -501,30 +496,59 @@ Should compile to use SMLAL (Signed Multiply Accumulate Long) which multiplies
 two signed 32-bit values to produce a 64-bit value, and accumulates this with 
 a 64-bit value.
 
-We currently get this with v6:
+We currently get this with both v4 and v6:
 
 _foo:
-        mul r12, r1, r0
-        smmul r1, r1, r0
-        smmul r0, r3, r2
-        mul r3, r3, r2
-        adds r3, r3, r12
-        adc r0, r0, r1
+        smull r1, r0, r1, r0
+        smull r3, r2, r3, r2
+        adds r3, r3, r1
+        adc r0, r2, r0
         bx lr
 
-and this with v4:
+//===---------------------------------------------------------------------===//
 
-_foo:
-        stmfd sp!, {r7, lr}
-        mov r7, sp
-        mul r12, r1, r0
-        smull r0, r1, r1, r0
-        smull lr, r0, r3, r2
-        mul r3, r3, r2
-        adds r3, r3, r12
-        adc r0, r0, r1
-        ldmfd sp!, {r7, pc}
-
-This apparently occurs in real code.
+This:
+        #include <algorithm>
+        std::pair<unsigned, bool> full_add(unsigned a, unsigned b)
+        { return std::make_pair(a + b, a + b < a); }
+        bool no_overflow(unsigned a, unsigned b)
+        { return !full_add(a, b).second; }
+
+Should compile to:
+
+_Z8full_addjj:
+       adds    r2, r1, r2
+       movcc   r1, #0
+       movcs   r1, #1
+       str     r2, [r0, #0]
+       strb    r1, [r0, #4]
+       mov     pc, lr
+
+_Z11no_overflowjj:
+       cmn     r0, r1
+       movcs   r0, #0
+       movcc   r0, #1
+       mov     pc, lr
+
+not:
+
+__Z8full_addjj:
+        add r3, r2, r1
+        str r3, [r0]
+        mov r2, #1
+        mov r12, #0
+        cmp r3, r1
+        movlo r12, r2
+        str r12, [r0, #+4]
+        bx lr
+__Z11no_overflowjj:
+        add r3, r1, r0
+        mov r2, #1
+        mov r1, #0
+        cmp r3, r0
+        movhs r1, r2
+        mov r0, r1
+        bx lr
 
 //===---------------------------------------------------------------------===//
+