From: George Koehler <xkernigh@netscape.net>
Date: Tue, 17 Oct 2017 21:00:28 +0000 (-0400)
Subject: Stop inlining code to convert integers to floats.
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=47bd0ef7a712b32555e8507fd0c5fbd9b8dcf318;p=ack.git

Stop inlining code to convert integers to floats.

Do the conversion by calling .cif8 or .cuf8 in libem, as it was done
before my commit 1de1e8f.  I used the inline conversion to experiment
with the register allocator, which was too slow until c5bb3be.

Now that libem has the only copy of the code, move some comments and
code changes there.
---

diff --git a/mach/powerpc/libem/cif8.s b/mach/powerpc/libem/cif8.s
index 13abbcade..7715769e6 100644
--- a/mach/powerpc/libem/cif8.s
+++ b/mach/powerpc/libem/cif8.s
@@ -8,25 +8,24 @@
 
 .define .cif8
 .cif8:
-	addi sp, sp, -4          ! make space for the double
+	! Conversion uses the pivot value
+	!   1 << 52 = 0x4330 0000 0000 0000
+	!
+	! From signed integer i, we compute
+	!   ((1 << 52) + (1 << 31) + i) - ((1 << 52) + (1 << 31))
+
+	lis r3, 0x4330
+	stwu r3, -4(sp)          ! make space for the double
 
 	lwz r3, 4(sp)
 	xoris r3, r3, 0x8000
-	stw r3, 4(sp)            ! flip sign of integer value
-
-	addis r3, r0, 0x4330
-	stw r3, 0(sp)            ! set high word to construct a double
+	stw r3, 4(sp)            ! flip sign bit to get (1 << 31) + i
 
-	lfd f0, 0(sp)            ! load value
-
-	lis r3, ha16[pivot]
-	lfd f1, lo16[pivot](r3)  ! load pivot value
-	fsub f0, f0, f1          ! adjust
+	lfd f0, 0(sp)            ! f0 = (1 << 52) + (1 << 31) + i
+	lis r3, 0x8000
+	stw r3, 4(sp)
+	lfd f1, 0(sp)            ! f1 = (1 << 52) + (1 << 31)
+	fsub f0, f0, f1          ! finish conversion
 
 	stfd f0, 0(sp)           ! save value again...
 	blr                      ! ...and return 
-
-.sect .rom
-pivot:
-	.data4 0x43300000
-	.data4 0x80000000
diff --git a/mach/powerpc/libem/cuf8.s b/mach/powerpc/libem/cuf8.s
index ce9932aa1..7a7af4505 100644
--- a/mach/powerpc/libem/cuf8.s
+++ b/mach/powerpc/libem/cuf8.s
@@ -6,21 +6,20 @@
 
 .define .cuf8
 .cuf8:
-	addi sp, sp, -4          ! make space for the double
+	! Conversion uses the pivot value
+	!   1 << 52 = 0x4330 0000 0000 0000
+	!
+	! From unsigned integer u, we compute
+	!   ((1 << 52) + u) - (1 << 52)
 
 	lis r3, 0x4330
-	stw r3, 0(sp)            ! set high word to construct a double
+	stwu r3, -4(sp)          ! make space for the double
 
-	lfd f0, 0(sp)            ! load value
-
-	lis r3, ha16[pivot]
-	lfd f1, lo16[pivot](r3)  ! load pivot value
-	fsub f0, f0, f1          ! adjust
+	lfd f0, 0(sp)            ! f0 = (1 << 52) + u
+	li r3, 0x0000
+	stw r3, 4(sp)
+	lfd f1, 0(sp)            ! f1 = (1 << 52)
+	fsub f0, f0, f1          ! finish conversion
 
 	stfd f0, 0(sp)           ! save value again...
 	blr                      ! ...and return
-
-.sect .rom
-pivot:
-	.data4 0x43300000
-	.data4 0x00000000
diff --git a/mach/powerpc/ncg/table b/mach/powerpc/ncg/table
index 151c03f3b..b6a7bfaa8 100644
--- a/mach/powerpc/ncg/table
+++ b/mach/powerpc/ncg/table
@@ -2353,48 +2353,15 @@ PATTERNS
 		leaving
 			cal ".cfu8"
 
-	/*
-	 * To convert integer to IEEE double, we pack the integer in
-	 * the low bits of the magic double
-	 *   1 << 52 == 0x 4330 0000 0000 0000
-	 *
-	 * For signed integer i, we flip its sign bit, then compute
-	 *   ((1 << 52) + i) - ((1 << 52) + (1 << 31))
-	 */
+	/* Convert signed int to double */
 	pat loc loc cif $1==4 && $2==8
-		with REG
-			uses reusing %1, REG={XOR_RIS, %1, 0x8000},
-			  REG={CONST_HZ, 0x43300000},
-			  REG={CONST_HZ, 0x80000000},
-			  FREG, FREG
-			gen
-				stwu %b, {IND_RC_W, sp, 0-8}
-				stw %a, {IND_RC_W, sp, 4}
-				lfd %d, {IND_RC_D, sp, 0}
-				stw %c, {IND_RC_W, sp, 4}
-				lfd %e, {IND_RC_D, sp, 0}
-				fsub %d, %d, %e
-				addi sp, sp, {CONST, 8}
-			yields %d
+		leaving
+			cal ".cif8"
 
-	/*
-	 * To convert unsigned integer u to IEEE double, we compute
-	 *   ((1 << 52) + u) - (1 << 52)
-	 */
+	/* Convert unsigned int to double */
 	pat loc loc cuf $1==4 && $2==8
-		with REG
-			uses REG={CONST_HZ, 0x43300000},
-			  REG={CONST_0000_7FFF, 0},
-			  FREG, FREG
-			gen
-				stwu %a, {IND_RC_W, sp, 0-8}
-				stw %1, {IND_RC_W, sp, 4}
-				lfd %c, {IND_RC_D, sp, 0}
-				stw %b, {IND_RC_W, sp, 4}
-				lfd %d, {IND_RC_D, sp, 0}
-				fsub %c, %c, %d
-				addi sp, sp, {CONST, 8}
-			yields %c
+		leaving
+			cal ".cuf8"
 
 	pat fef $1==8                      /* Split fraction, exponent */
 		leaving